Trump-Biden transition updates: At least 20 arrested, 1 stabbed at DC protests

Trump earlier Wednesday met with senior advisers including Jared Kushner, Jason Miller and campaign manager Bill Stepien to discuss a post-election path forward as he publicly refuses to concede the election, multiple sources told ABC News.

It's not necessarily unusual for the president to meet with senior advisers, but the meeting comes as the campaign continues pushing legal battles in several key states to dispute the election results. Trump has held several meetings with this group and other top aides since last week's election.

-ABC News Chief White House correspondent Jonathan Karl, Will Steakin, John Santucci and Katherine Faulders

The refusal of a General Services Administration to acknowledge Biden's election victory is stalling the president-elect's ability to prepare for taking office, and opening what experts called "dangerous gaps" in the nation's security heading into the transfer of power.

"It is deeply in our national interest to reduce the disruptions in a transition and try to make this go smoothly," said Lee Hamilton, a former Democratic congressman from Indiana who has studied the issue. "The transition is a period of potential danger and increased risk to the country … and our adversaries know that."

Years after the Sept. 11 terrorist attacks, the authors of the 9/11 Commission Report determined that the compressed transition timeframe ahead of George W. Bush's inauguration "hampered the new administration in identifying, recruiting, clearing, and obtaining Senate confirmation of key appointees."

Hamilton, who co-authored the 9/11 Commission Report, said Wednesday that those delays contributed to challenges in responding to the attacks and failure to address those delays opens up "dangerous gaps in the security posture of the United States."

-ABC News' Lucien Bruggeman

Biden is expected to name his White House chief of staff as soon as this week, multiple sources familiar with the matter told ABC News.

The announcement of a chief of staff typically comes as one of the first big decisions for a president-elect -- crucial because the person in that role can help determine a president’s style of governing.

Biden’s former chief of staff Ron Klain, who led the Obama administration’s response to the Ebola virus, is considered a leading contender, in part because of the urgent need to deal with the coronavirus pandemic.

Other names on Biden's short list are said to be Steve Richetti -- a candidate opposed by progressives for his work as a lobbyist -- and Bruce Reed, also both former chiefs of staff to Biden.

-ABC News' Katherine Faulders, Molly Nagle, Benajmin Siegel and John Santucci

David Marchick, director of the Center for Presidential Transition, a nonpartisan group that helps candidates and presidents prepare for the transition of power, told ABC News Live’s “The Breakdown” Wednesday afternoon it’s “absolutely imperative” Biden’s transition goes smoothly and that it's is a matter of national security.

“What history shows is that transitions are a time of vulnerability where our adversaries seem to take advantage of the United States, and this is perhaps the most important transition the United States will experience since 1932 when we were in the depth of the Great Depression,” Marchick said. 

His comments come as the Biden transition team is in a standoff with the General Services Administration (GSA) which, typically, recognizes a candidate that has clearly won the election to allow the winning ticket's team to access federal resources available to aid the transition process.

GSA Administrator Emily Murphy, who was appointed by Trump in 2017, has made no such determination.

"This act called ascertainment has never been politicized,” Marchick added. “It's always been granted within 24 hours of the outcome of an election being clear.”

Marchick said the one exception was in 2000 with Bush vs. Gore, but stressed that delay was only caused by one state and 537 votes. In 2020, he said, Biden’s winning margins in several key states surpass Trump by more than 10,000 votes. 

“Here the outcome, as former President Bush himself said, is clear and it's critical that the ascertainment go forward,” he added.