WASHINGTON (AP) — The Latest on President-elect Joe Biden (all times local):

1:55 p.m.

The U.S. Chamber of Commerce says it would like to see a major infrastructure bill as the first order of business for a Biden-Harris administration and a new Congress in 2021.

The powerful business lobby group had teamed up with the AFL-CIO and other groups during Donald Trump's presidency to push for significant new investments in roads, bridges and broadband but could not get legislation over the finish line. How to pay for such investment remains a huge stumbling block.

Neil Bradley, an executive vice president at the business group, says the chamber will continue to push the Trump administration and Congress to get an economic relief bill passed before the end of the year to help businesses survive during the coronavirus pandemic.

He says the economic recovery is “uneven across industries and across communities, and we have to focus on those who will be the last to recover from this pandemic induced recession.”

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HERE'S WHAT YOU NEED TO KNOW ABOUT PRESIDENT-ELECT JOE BIDEN'S TRANSITION TO THE WHITE HOUSE:

President-elect Joe Biden is cheering news about the promising development of a coronavirus vaccine but cautioning Americans need to be aggressive about mask wearing and social distancing.

Read more:

— Trump faces calls to work with Biden team on transition

— Members of President-elect Biden’s coronavirus task force

— Referendum on Trump shatters turnout records

— For Biden, how to help mangled economy is next obstacle

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HERE'S WHAT ELSE IS GOING ON:

1:50 p.m.

The highest-ranking Black member of Congress is urging President Donald Trump to stop challenging the results of the 2020 general election and begin finding ways to work with the incoming administration of President-elect Joe Biden.

Clyburn said Monday during a media availability that Trump appears to be “hell-bent on destroying the fabric that’s been holding” the country together by alleging unsubstantiated fraud in the vote counting.

Applauding the Biden transition team’s work in setting up a coronavirus task force, Clyburn said he has “absolutely no interest” in a post of his own in the administration. But he did suggest that Jaime Harrison, who recently lost to Sen. Lindsey Graham of South Carolina, might be a good pick.

Harrison told The Associated Press on Monday that he would be willing to serve. He says, “If the president-elect asks you to serve, then you serve." He says he would leave it up to the Biden team to determine what post would be a good fit.

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1:45 p.m.

The White House is instructing federal agencies to fire political appointees of President Donald Trump who are looking for job opportunities after Trump’s election defeat to President-elect Joe Biden.

A senior administration official says presidential personnel director John McEntee, the president’s former personal aide, told White House liaisons at departments that they should terminate any political appointees seeking new work while Trump has refused to accept the electoral results.

The official spoke on condition of anonymity to discuss private conversations.

Trump’s term ends at noon on Jan. 20. Several thousand political appointees across the government will see their jobs end by that date.

Biden was declared the winner of the presidential election on Saturday.

— By AP writer Zeke Miller

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1:35 p.m.

U.N. Secretary-General Antonio Guterres is congratulating President-elect Joe Biden and Vice President-elect Kamala Harris while reaffirming the U.S.-U.N. partnership as “an essential pillar of the international cooperation needed to address the dramatic challenges facing the world today.”

The message, delivered Monday by U.N. spokesperson Stephane Dujarric, also congratulated the American people “for a vibrant exercise of democracy in their country’s elections last week.”

Dujarric said in response to a question on Harris’ historic victory as the first woman to be elected vice president that the secretary-general is always pleased and welcomes a woman getting “to break a new ceiling.”

General Assembly President Volkan Bozkir tweeted his warmest congratulations to Biden, citing his “long history” of supporting the United Nations, and to Harris for her historic election, which he called “a milestone for gender equality.”

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1 p.m.

President Donald Trump has fired Defense Secretary Mark Esper, a stunning move on the heels of Trump’s failed reelection bid.

Presidents who win reelection often replace Cabinet members, including the secretary of defense, but losing presidents have kept their Pentagon chiefs in place until Inauguration Day to preserve stability in the name of national security.

Trump announced the news in a tweet, saying that “effective immediately” Christopher Miller, the director of the National Counterterrorism Center, will serve as acting secretary, sidestepping the department’s No.2-ranking official, Deputy Defense Secretary David Norquist.

“Chris will do a GREAT job!” Trump tweeted. “Mark Esper has been terminated. I would like to thank him for his service.”

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12:50 p.m.

Housing and Urban Development Secretary Ben Carson has tested positive for the coronavirus. Carson is the first member of President Donald Trump’s cabinet known to have tested positive.

The department’s deputy chief of staff, Coalter Baker, said Monday that Carson is “in good spirits and feels fortunate to have access to effective therapeutics which aid and markedly speed his recovery.”

The 69-year-old Carson is among several top Trump administration officials who attended last week’s election night party at the White House. Carson has been a steadfast surrogate for the Republican president, traveling to many of the swing states before Election Day to discuss the administration’s priorities and achievements. Carson attended several events Trump held to appeal to African American voters.

Before joining the Trump administration, Carson had sought the GOP’s presidential nomination in 2016. He served for nearly 30 years as director of pediatric neurosurgery at the Johns Hopkins Children’s Center.

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12:15 p.m.

President-elect Joe Biden is imploring Americans to “wear a mask” to help fight the spread of the coronavirus — “no matter who you voted for.”

He says, “We are Americans, and our country is under threat.”

The Democrat said Monday wearing masks could slow the death toll in the COVID-19 pandemic, which he noted could climb by 200,000 before a vaccine is widely available.

Biden said, “Please, I implore you, wear a mask.” He noted masks could save the lives of older people, children and teachers and added: “It could even save your own life.”

Biden notes that he doesn’t take office until Jan. 20 but is assuming a public leadership role in the fight against the pandemic ahead of being sworn in.

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12:05 p.m.

President-elect Joe Biden is warning the United States is “still facing a very dark winter” as he unveils plans for addressing COVID-19 pandemic.

Even as hopes of a vaccine lifted stocks, Biden said Monday another 200,000 lives could be lost before it is widely available. Biden implores Americans to “wear a mask.”

Biden says he would be guided by science in laying out the framework of a pandemic response, starting with members of a task force to prepare for his administration’s transition to overseeing it.

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11:20 a.m.

One week after Election Day, Vice President Mike Pence appears ready to take some time off.

According to the Federal Aviation Administration, Pence is scheduled to travel to Sanibel, Florida, Tuesday through Saturday. Pence has vacationed on the island along Florida’s Gulf Coast several times previously. Pence’s office didn’t immediately comment on the trip on Monday.

The trip comes as President Donald Trump has pledged to continue trying to contest the outcome of the election and as President-elect Joe Biden is ramping up his transition efforts.

Biden and Vice President-elect Kamala Harris are being briefed virtually on the coronavirus pandemic by a task force of experts their transition team announced Monday.

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11:10 a.m.

Joe Biden and Kamala Harris are being briefed virtually on the coronavirus pandemic by a task force of experts their transition team announced only hours earlier.

The Democratic president-elect and vice president-elect sat at separate, individual socially distanced tables and took notes as the members introduced themselves on Monday.

Biden is also planning to give a speech on his planned response to the pandemic. Then Biden and Harris will hold hours of internal meetings about transitioning to the White House in January.

The task force briefing was at the Queen, a theater in downtown Wilmington, Delaware, where Biden’s campaign built a studio and other communications infrastructure and has spent months organizing virtual meetings and speeches.

The first to speak during the briefing was former Food Drug Administration Commissioner Dr. David Kessler. He is co-chairing the task force with former Surgeon General Dr. Vivek Murthy and Dr. Marcella Nunez-Smith, a Yale University associate professor and associate dean whose research focuses on promoting health care equality for marginalized populations.

Also part of the group is Rick Bright, a whistleblower who was demoted after criticizing the Trump administration’s pandemic response. Bright had been head of the Biomedical Advanced Research and Development Authority.

Journalists could watch only about two minutes of the proceedings and heard only the participants introducing themselves.

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7:25 a.m.

President-elect Joe Biden has announced the members of his coronavirus task force, which will put together a blueprint for fighting the pandemic.

The co-chairs are former Surgeon General Dr. Vivek Murthy, former Food Drug Administration Commissioner Dr. David Kessler and Dr. Marcella Nunez-Smith, a Yale University professor and researcher.

Notable among the task force members is Rick Bright, a vaccine expert and former head of the Biomedical Advanced Research and Development Authority. Bright filed a whistleblower complaint alleging he was reassigned to a lesser job because he resisted political pressure to allow widespread use of hydroxychloroquine, a malaria drug pushed by President Donald Trump as a COVID-19 treatment.

Other members include Luciana Borio, a biodefense specialist; Dr. Ezekiel Emanuel, an oncologist and bioethics chair at the National Institutes of Health; Dr. Atul Gawande, a Clinton administration health advisor and surgery expert; Dr. Celine Gounder, an infectious disease expert who has studied HIV/AIDS and tuberculosis; Dr. Julie Morita, a pediatric and immunization specialist; Dr. Michael Osterholm, an infectious disease expert and epidemiologist; Loyce Pace, a global health specialist; Dr. Robert Rodriguez, an emergency medicine expert who has researched mental health of COVID-19 responders; and Dr. Eric Goosby, an infectious disease expert who has worked in AIDS/HIV.

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