President-elect Joseph R. Biden Jr. excoriated the Trump administration for its failure to prioritize cybersecurity over the past four years, blaming the recent penetration of United States government agencies by Russian hackers on President Trump.
“This assault happened on Donald Trump’s watch when he wasn’t watching,” Mr. Biden said at a year-end news conference in Wilmington, Del., blaming him for what he called “irrational downplaying of the seriousness of this attack.”
“Even if he doesn’t take it seriously, I will,” Mr. Biden said. “I’m disappointed by the response of President Trump.”
“This president hasn’t even identified who is responsible yet,” he said, adding that Mr. Trump’s “failure will land on my doorstep” next year when he takes office.
It was an impassioned denunciation from a president-elect who has generally tried to strike a tone of unity, and who as recently as Monday even credited the Trump administration for the speed with which it helped get out a vaccine.
Mr. Biden noted with frustration that “the Defense Department won’t even brief us,” a reference to transition meetings that the acting defense secretary, Christopher Miller, canceled last week for the holidays, falsely claiming it was a mutual decision to do so. But he noted that “leaders in both parties in Congress” condemned Russia for the hack.
Mr. Trump has remained out of sight in the days ahead of Christmas, nursing grievances about his election loss and saying little about the Russian hack, the stimulus bill or even the rollout of a vaccine his advisers want him to take credit for.
Mr. Biden stepped into that void on Tuesday, a day after Congress passed $900 billion in coronavirus relief, calling the package a “down payment” on a bigger bill. He exhorted Congress to return to the negotiating table while urging Americans to take precautions to avoid taking part in holiday gatherings that could lead to a new spike in infections.
“Congress did its job this week,” he said. “I can and I must ask them to do it again next year,” he added, referring to more congressional stimulus spending to combat the coronavirus.
Mr. Biden said he planned to put forward to Congress in the new year a plan that would include more funding to help firefighters, police officers and nurses, as well as to expand testing. He said his bill would include a new round of stimulus checks to Americans, but he said how much would be a matter of negotiation.
His focus, he said, was to have the money necessary to distribute the vaccine to 300 million people, to provide aid to Americans whose businesses have been shuttered because of the virus and to place a moratorium on evictions.
“People are desperately hurting,” he said. Ahead of Christmas, and the potential gatherings that may lead to more spikes in virus cases, Mr. Biden also warned Americans that “our darkest days are ahead of us, not behind us.”
Mr. Trump intends to sign the funding bill. But he has otherwise chosen to play a minor role in the midst of a major national crisis — consumed by conspiracy theories about election fraud at a moment when the daily death toll of the pandemic routinely exceeds the number of Americans killed in the Pearl Harbor attack.
On Tuesday, he unleashed a familiar fusillade of false claims about the 2020 election on Twitter, interrupted by one post on the virus — a boast about “the great miracle of what the Trump Administration has accomplished” on vaccines.
Mr. Biden did not negotiate with lawmakers on the stimulus directly, but he was apprised of all developments, and his incoming chief of staff, Ron Klain, was kept abreast of the hour-by-hour developments in the talks, according to Democratic officials familiar with the situation.
Mr. Trump had no public events scheduled on Tuesday, although pool reporters covering the White House were told to stand by for his official signing of the pandemic relief package.
Mr. Trump’s signature on the deal was essential, but his presence during its negotiations was not, with most of the details hammered out by the Treasury secretary, Steven Mnuchin, and legislative leaders from both parties. Republicans on the Hill have long thought it best to keep Mr. Trump at a distance and have not clambered for more involvement.
The president’s one significant intervention in the talks seems to have been a fleeting call for $2,000 stimulus checks for families hurt economically by the pandemic. It was ignored by Senate Republicans, who agreed on a payout of $600.
And this is, ironically, where both Mr. Trump and Mr. Biden agree — that the checks are not big enough.
Hundreds of dollars in direct payments may start going to American households as soon as next week after Congress overwhelmingly passed a $900 billion stimulus package sending billions of dollars to individuals and businesses grappling with the economic and health toll of the coronavirus pandemic.
The long-sought relief package was part of a $2.3 trillion catchall package that included $1.4 trillion to fund the government through the end of the fiscal year on Sept. 30. It included the extension of routine tax provisions, a tax deduction for corporate meals, the establishment of two Smithsonian museums, a ban on surprise medical bills and a restoration of Pell grants for incarcerated students, among hundreds of other measures.
Though the $900 billion stimulus package is half the size of the $2.2 trillion stimulus law passed in March that provided the core of its legislative provisions, it remains one of the largest relief packages in modern American history. It will revive a supplemental unemployment benefit for millions of unemployed Americans at $300 a week for 11 weeks and provide for another round of $600 direct payments to adults and children.
“I expect we’ll get the money out by the beginning of next week — $2,400 for a family of four — so much needed relief just in time for the holidays,” Treasury Secretary Steven Mnuchin said on CNBC. “I think this will take us through the recovery.”
President-elect Joseph R. Biden Jr., who received a coronavirus vaccine on Monday with television cameras rolling, has insisted that this bill is only the beginning, and that more relief, especially to state and local governments, will be coming after his inauguration next month.
Lawmakers hustled on Monday to pass the bill, nearly 5,600 pages long, less than 24 hours after its completion and before virtually anyone had read it. At one point, aides struggled simply to put the measure online because of a corrupted computer file.
The legislative text is likely to be one of the longest ever, and it became available only a few hours before both chambers approved the bill. In the Senate, the bill passed 92 to 6. It will now go to President Trump for his signature.
Alex Padilla, California’s secretary of state, has been appointed to fill the Senate seat held by Vice President-elect Kamala Harris, Gov. Gavin Newsom announced on Tuesday, capping months of intense political jockeying among Democratic factions in the state.
The son of Mexican-born immigrants who settled in Los Angeles’s San Fernando Valley, Mr. Padilla, 47, will be the first Latino senator from California, where Latinos are about 40 percent of the population.
“I am honored and humbled by the trust placed in me by Governor Newsom, and I intend to work each and every day to honor that trust and deliver for all Californians,” said Mr. Padilla in a statement.
“From those struggling to make ends meet to the small businesses fighting to keep their doors open to the health care workers looking for relief, please know that I am going to the Senate to fight for you. We will get through this pandemic together and rebuild our economy in a way that doesn’t leave working families behind.”
His appointment will make history. But the @AlexPadilla4CA I know is far more interested in changing history — especially for the working men and women of our state and country.
I can think of no one better to represent the state of California as our next United States Senator. pic.twitter.com/xiAzpTS42Y
— Gavin Newsom (@GavinNewsom) December 22, 2020
Mr. Padilla, an ally of the governor throughout his political career, has held public office since 1999, when he was elected at 26 to the Los Angeles City Council; he went on to serve two terms in the State Senate and then two terms as secretary of state, heading the office that runs California’s elections.
The decision followed months of deliberation by Mr. Newsom and lobbying by California’s myriad political factions for a position whose occupant will need not only the experience to work effectively in Washington, but also the money and political base to hold the seat in 2022, when Ms. Harris’s term ends.
California progressives had pushed Mr. Newsom to appoint Representative Barbara Lee or another like-minded Democrat. Mr. Newsom was also under pressure to appoint a Black woman to take the place of Ms. Harris, the only Black woman in the Senate. Representative Karen Bass and Ms. Lee were at the top of that list.
As weeks passed after the presidential election, the back-channel advocacy that had gone on since Ms. Harris was chosen as the running mate of President-elect Joseph R. Biden Jr. broke into the open with public endorsements, full-page newspaper ads and open letters. The Congressional Hispanic Caucus strongly backed Mr. Padilla. The L.G.B.T.Q. community and Equality California lobbied for Robert Garcia, the mayor of Long Beach. Black Women United, a co-founder of Black Lives Matter and a range of Black elected officials pushed for Ms. Bass or Ms. Lee.
California’s senior senator, Dianne Feinstein, endorsed Mr. Padilla, who had worked in her field office early in his career. But other interest groups wanted Ms. Feinstein herself to step down — a call that gained traction after a New Yorker article this month suggested that Ms. Feinstein, 87, was experiencing cognitive decline.
The elevation of Mr. Padilla leaves Mr. Newsom with a vacancy in the secretary of state’s office, a potential consolation prize for at least one disappointed contender. He will also have to appoint a new attorney general if the Senate confirms Xavier Becerra’s nomination as Mr. Biden’s secretary of health and human services.
The attorney general post, in particular, has in recent years served as a springboard for higher office; besides Mr. Becerra, recent attorneys general include Ms. Harris and California’s previous governor, Jerry Brown.
Alex Padilla, who was tapped by Gov. Gavin Newsom of California to fill Vice President-elect Kamala Harris’s Senate seat on Tuesday, will become the state’s first Latino senator.
“Amazing news for Latinos in California and across the country!” wrote Luis V. Gutierrez, a former Democratic congressman from Illinois, in a tweet that reflected the jubilation of many who thought the development long overdue in a state where 40 percent of the population identifies as Latino.
But while the appointment of Mr. Padilla, California’s secretary of state, represents a groundbreaking addition, it also entails a sobering subtraction: His selection means there will not be a single Black woman in the Senate.
“Today’s decision, unfortunately, leaves us with one less woman and now not a single Black woman in the United States Senate, chipping away at decades of progress that have been made to ensure our United States Senate looks like the America it represents,” wrote Aimee Allison, founder of She the People, a national organization that promotes the election and appointment of Black women to positions of power.
Ms. Allison and others had pushed Mr. Newsom, who is close to Mr. Padilla, to appoint a Black woman to replace Ms. Harris, with suggestions including Representatives Barbara Lee and Karen Bass. Members of the Congressional Hispanic Caucus supported the appointment of Mr. Padilla.
“It is ok to simultaneously be sad that there will be no black woman in the US Senate, and happy about an Alex Padilla appointment,” wrote Stephanie Clay, a comic-book writer from Houston, summing up the views of many Democrats on social media.
Ms. Lee, on Twitter, congratulated Mr. Padilla as “a skilled legislator and a steadfast advocate for justice.” “I believe he will be a powerful voice in the Senate for those who continue to be denied our country’s promise of equality,” she said.
Mr. Padilla’s personal history — he is the son of immigrants from Mexico who worked his way through M.I.T. and to the heights of political power in the nation’s most populous state — was a deeply familiar one to many Latinos, even if his presence will be a relative novelty in the Senate.
“Congratulations to Alex Padilla on his historic appt to the U.S. Senate!” wrote Representative Nanette Diaz Barragán, a Democrat from Los Angeles, noting that the state had never sent a Latino to the Senate despite its large Latino population. “The time is now.”
President-elect Joseph R. Biden Jr. is expected to nominate Miguel A. Cardona, Connecticut’s education commissioner, to serve as his education secretary, tapping a Latino to be the nation’s highest education policymaker, according to two officials familiar with his plans.
Dr. Cardona, if confirmed by the Senate, would be tasked with bringing the elementary, secondary and higher education systems back from the disruption caused by the coronavirus pandemic and repairing the considerable damage done. School districts, colleges and universities have hemorrhaged money as they struggled with distance learning, retrofitted buildings to make them somewhat safer, and lost students, especially foreign university students who had been paying full tuition.
The pandemic has also widened the achievement gap between affluent students and poorer pupils who fell behind as they suffered through deficient internet access and difficult home-learning conditions.
The selection of Dr. Cardona would fulfill Mr. Biden’s campaign promise to appoint a diverse cabinet and a secretary of education with public school experience — a blunt juxtaposition to President Trump’s billionaire private-school champion Betsy DeVos. The official announcement is expected as soon as Tuesday. Dr. Cardona had not been offered the job as of Tuesday morning, according to a person familiar with the discussions.
Dr. Cardona was appointed Connecticut’s first Latino commissioner of education in 2019 after two decades of experience as a public school educator, starting in a Meriden, Conn., elementary school classroom, according to his official biography. He also served as a principal for a decade, among the youngest in the state, and as assistant superintendent and adjunct professor at the University of Connecticut.
Dr. Cardona emerged as a front-runner for the position in recent days, beating out teachers union leaders, higher education academics, and superintendents of large, urban school districts. He garnered the endorsements of important stakeholders in the Biden campaign, including congressional leaders, teachers unions, community groups and one of Mr. Biden’s early preferred candidates, Linda Darling-Hammond, who headed the campaign’s education transition team but took herself out of the running.
An analysis of new Census Bureau data gives an early glimpse of how the nation’s legislative map might change after the results of the 2020 census next year.
Every decade, the Census Bureau adjusts the number of seats assigned to each state in the House of Representatives based on changes in its population as measured by the decennial census, in a process called reapportionment. The process also changes the total number of votes that each state has in the Electoral College, which mirrors the size of its congressional delegation — the sum of its number of House seats and two senators.
Tuesday’s analysis, by William Frey, chief demographer for the Brookings Institution, is the best guess, given the data available now, of what that future map might look like. The Census Bureau will release the results of the 2020 census next year, and with it, the new state map.
California would lose one of its seats in the House for the first time, bringing it to 52, according to the analysis, reflecting the state’s sluggish growth pattern. Each of the following states would also lose one seat: Alabama, Illinois, Michigan, Minnesota, New York, Ohio, West Virginia, Pennsylvania and Rhode Island.
New York would drop to 26 seats, leaving it with fewer than Florida for the first time. Florida would gain two, bringing it to 29 and lifting it to third place in the tally, after California and Texas.
The biggest gains would be mostly in the South and West. Texas would gain three seats, giving it 39, while Arizona, Colorado, Oregon, North Carolina and Montana would each gain one seat.
Mr. Frey used the Bureau’s population estimates, which were released on Tuesday and show population growth from July 2019 to July 2020. He combined them with similar estimates over the last decade, and then applied an algorithm designed to calculate reapportionment by experts at the University of Michigan’s Population Studies Center.
In the year that ended July 1, 2020, the United States population grew at its slowest rate since around 1900, when the government began conducting these annual estimates. That was partly an effect of the coronavirus pandemic, which has claimed thousands of American lives since March. But growth slowed substantially even before the virus, as fertility rates languished and immigration dwindled.
In a message intended to fend off a rush of migrants to the southern border, the incoming Biden administration announced on Tuesday that it would not immediately reverse the restrictions imposed by President Trump that have effectively halted asylum and left thousands of people stranded outside the United States.
Transition officials, speaking to reporters on the condition of anonymity to discuss for the first time plans for the border, said that they would eventually resume processing of asylum seekers at ports of entry along the border. But those officials said that initially, only a limited number of migrants would be allowed to have their claims heard.
Immigrant advocates and human-rights groups have derided Trump administration measures to bar most people from entering the United States and called for the new administration to swiftly take steps to roll back some of them, something President-elect Joseph R. Biden Jr. had suggested that he would do.
Yet quickly undoing Trump administration policies could be construed as rolling out the welcome mat, risking a surge in arrivals that could devolve into a humanitarian crisis for a new administration trying to focus on taming the raging Covid-19 pandemic and revitalizing the economy.
The transition officials blamed the Trump administration for gutting the asylum system, saying it would take considerable time and effort to rebuild the infrastructure to process migrants’ claims. They also cited the public health crisis as justification for not reopening the border right away.
“The Biden administration will start processing asylum claims at the ports of entry but it will be a gradual start because of lack of personnel and infrastructure,” said one of the officials.
Susan E. Rice, the incoming domestic policy adviser, said on Monday that “Processing power at the border is not like a light that can be turned on and off.”
“Migrants and asylum seekers should not at all believe the people in the region who are selling the idea that the border will suddenly be wide open to process everyone on the first day,” Ms. Rice told the Spanish-language wire service EFE. “It will not be so.”
Dr. Anthony S. Fauci, the government’s top infectious disease expert, was vaccinated on Tuesday during a live broadcast of what the National Institutes of Health called a kickoff event showcasing Moderna’s vaccine, which was developed by scientists at the agency and received emergency authorization from the Food and Drug Administration on Friday.
Rolling up the sleeve of a blue dress shirt, Dr. Fauci called his public vaccination “a symbol to the rest of the country that I feel extreme confidence in the safety and the efficacy of this vaccine.”
“I want to encourage everyone who has the opportunity to get vaccinated so that we can have a veil of protection over this country that would end this pandemic,” he said.
Joining Dr. Fauci in an auditorium at N.I.H. to receive vaccinations were Dr. Francis S. Collins, the agency’s director, Alex M. Azar II, the health and human services secretary, and frontline workers at the N.I.H. Clinical Center. They will receive the second dose of the Moderna vaccine in 28 days.
The Moderna vaccine, which has received billions of dollars of support from the federal government, has become a triumphant symbol of the administration’s efforts to develop and distribute a vaccine. It was designed by scientists at N.I.H. and the company within two days of China’s releasing the genetic sequence of the coronavirus.
“What we’re seeing now is the culmination of years of research, which have led to a phenomenon that has truly been unprecedented,” Dr. Fauci said at the Tuesday event. “And that is to go from the realization that we’re dealing with a new pathogen, a virus that was described in January of this year, to less than one year later to have vaccines that are going into the arms of so many people, including myself.”
Dr. Fauci’s vaccination was long awaited by public figures and health experts. Former President Barack Obama recently said that if Dr. Fauci, who will also be the chief medical adviser to President-elect Joseph R. Biden Jr. once he takes office, endorses a coronavirus vaccine, that would be a signal to him that it is safe.
On Monday, Mr. Biden received a coronavirus vaccine on live television at the Christiana Hospital in Newark, Del., to send a message to Americans across the country that the vaccine was safe to take.
“Left’s good,” he told the nurse practitioner who administered the Pfizer-BioNTech Covid-19 vaccine, rolling up the sleeve of his black long-sleeve turtleneck and exposing his left arm. “You just go ahead anytime you’re ready.”
He credited the Trump administration for its work on Operation Warp Speed, which helped to deliver a quick vaccine.
“The administration deserves some credit getting this off the ground,” he said. “I’m doing this to demonstrate that people should be prepared when it’s available to take the vaccine.”
Mr. Biden, however, warned Americans that vigilance in the coming months was still necessary.
“It’s going to take time,” he said, encouraging people to continue to wear masks and socially distance. “If you don’t have to travel, don’t travel,” he said. “It’s really important.”
Since March, Mr. Biden’s team has been taking public health guidelines about social distancing and masks seriously, as President Trump and his aides have willfully disregarded them. But even Mr. Biden’s more careful circle has been infiltrated by the virus. Representative Cedric L. Richmond, Democrat of Louisiana and one of Mr. Biden’s closest advisers, tested positive for the coronavirus last week, the transition team announced.
Vice President-elect Kamala Harris is expected to receive her vaccine after Christmas, a spokeswoman said, following advice from doctors who recommended Mr. Biden and Ms. Harris stagger their first shots rather than receive them together.
The overdue pandemic aid package represents both a pre-inaugural legislative victory for President-elect Joseph R. Biden Jr. and a potential template for congressional deal-making in the coming Biden era.
Along with struggling Americans and businesses, the incoming president was a major beneficiary of the $900 billion pandemic stimulus measure that passed on Monday night, which will give him some breathing room when he enters the White House next month. Rather than face an immediate and dire need to act on an emergency economic aid package, Mr. Biden and his team can take a moment to instead try to fashion a more far-reaching recovery program and begin to tackle other issues.
“President-elect Biden is going to have an economy that is healthier,” said Senator Mark Warner, Democrat of Virginia and one of the chief players in a breakaway effort by centrists in the Senate and House that led to the compromise.
Given the slender partisan divides that will exist in both the Senate and House next year, the approach could provide a road map for the Biden administration if it hopes to break through congressional paralysis, especially in the Senate, and pass additional legislation. Mr. Biden has said another economic relief plan will be an early priority.
“I believe it is going to be the only way we are going to accomplish the president-elect’s agenda in the next two years,” said Representative Josh Gottheimer, Democrat of New Jersey and a leader of the 50-member bipartisan Problem Solvers Caucus that took part in forging the compromise. “In the long run, this is the way to govern.”
Mr. Biden on Sunday applauded the willingness of lawmakers to “reach across the aisle” and called the effort a “model for the challenging work ahead for our nation.” He was also not an idle bystander in the negotiations.
Mr. Biden’s move was not without risks. If it had failed to impact the discussions, the president-elect risked looking powerless to move Congress, even before he had taken the oath of office. But members of both parties said his intervention was constructive and gave Democrats confidence in lowering their demands.
Tucked into Congress’s voluminous stimulus package are significant changes to higher-education law, including a resumption of federal financial aid to prison inmates that was banned in the 1994 crime bill championed by then-Senator Joseph R. Biden Jr.
The restoration of Pell grants for prisoners is something of a watershed moment for the criminal justice overhaul movement, which is seeking to unwind decades of punitive practices in favor of finding avenues to reintegrate incarcerated people into society.
The measure was part of a bipartisan deal struck by House and Senate education leaders to address affordability and equity in higher education. It was attached to the $900 billion stimulus bill making its way to President Trump’s desk. The package also includes the simplification of the federal financial aid application process, a significant expansion of students eligible for federal aid, and the forgiveness of more than $1 billion in federal loans held by historically Black colleges and universities.
For two years, efforts to rewrite the Higher Education Act have stalled repeatedly as leaders wrestled with polarizing issues, like college affordability and campus sexual assault. But with Senator Lamar Alexander, Republican of Tennessee and the chairman of the Senate Education Committee, leaving Congress this year and looking for a legacy accomplishment, Democrats seized the opportunity to secure long-sought policy wins that address some of the racial and financial inequities highlighted by the unrest of the past year.
Dana Nessel, Michigan’s attorney general, said she planned to ask for sanctions against and legal fees from some of the lawyers who filed lawsuits over how Michigan’s elections were run.
“We’ll go to the Attorney Grievance Commission on some cases, where we know for a fact that there were intentional misrepresentations that were made, the kind where there is no question of the facts,” she told reporters on Tuesday. “If you have your name attached to it and you’ve made intentional misrepresentations, I absolutely think you ought to be held accountable.”
The Trump campaign or allies of the president have filed multiple lawsuits in Michigan over the election results in the state, where President-elect Joseph R. Biden Jr. won by more than 150,000 votes. The lawsuits have been either dismissed or withdrawn from county, state and federal courts by judges who have called the claims baseless and the witness statements not credible.
Some of the lawsuits have repeated claims that had already been dismissed by other courts. Most have dealt with either baseless claims of voter fraud or the counting of absentee ballots in Detroit. Some of the lawsuits asked that the absentee votes of more than 170,000 Detroiters, 94 percent of which went to Mr. Biden, be thrown out.
Ms. Nessel said she was prepared to lodge complaints with watchdog groups in other states, including one against the Texas lawyer Sidney Powell, who has filed multiple lawsuits with fanciful claims about foreign interference in voting systems used by some of the counties in the state. Rudolph W. Giuliani, one of Mr. Trump’s personal lawyers, is unlikely to be the subject of a complaint, even though he appeared in Michigan to testify before a committee of the State Legislature looking into alleged election irregularities.
“He testified, but he wasn’t put under oath,” she said. “If he had lied under oath, he could have been subject to prosecution.”
The costs associated with defending the state against the election lawsuits are being determined now, Ms. Nessel said.
The city of Detroit also has asked a federal judge to sanction Ms. Powell and other lawyers involved in a now-dismissed lawsuit against the city and other election officials, including barring them from practicing in the U.S. District Court in Detroit.
In the waning days of the 116th Congress, lawmakers have authorized $35 billion in spending on wind, solar and other clean power sources while curtailing the use of a potent planet-warming chemical used in air-conditioners and refrigerators.
Both measures, backed by some of the Senate’s most powerful Republicans, were attached to the huge government spending and coronavirus relief package that passed Monday night and was expected to be signed by President Trump in the coming days, effectively creating the first significant climate change law since at least 2009.
They amount to a rare party rebuke to Mr. Trump on the issue of global warming, after he spent the past four years mocking and systematically rolling back every major climate change rule. The comity may also signal that while President-elect Joseph R. Biden Jr. is unlikely to secure his full climate plan, he may be able to make some progress in curbing global warming.
Senator Chuck Schumer of New York, the Democratic leader, called the effort “the single biggest victory in the fight against climate change to pass this body in a decade.”
Senator John Barrasso, Republican of Wyoming and a leading opponent of most climate change policies, also celebrated: “This agreement protects both American consumers and American businesses,” he said. “We can have clean air without damaging our economy.”
Advocates for climate change policy said passage of the climate measures — especially the limits on refrigerants — could signal to the rest of the world that the United States is ready to rejoin the global effort to slow the warming of the planet. The coolant phase-down would be one of the most significant federal policies ever taken to cut greenhouse gas emissions, according to an analysis by the Rhodium Group, a research and consulting firm.
By 2035, the law would help avoid the equivalent of 949 million tons of carbon dioxide, the group estimated, which is similar in scope to the extra expected emissions from Mr. Trump’s climate policy rollbacks on vehicle pollution and methane from oil and gas operations.
Mr. Biden has pledged to enact the most ambitious climate change agenda by a president. On his Inauguration Day he is expected to formally rejoin the Paris agreement, the 2015 pact under which nearly every country agreed to reduce greenhouse gas emissions. Mr. Trump formally withdrew the United States from the agreement in November. Mr. Biden has also pledged to host a global climate summit in Washington within the first 100 days of his administration.