President Biden has rejected an attempt by Donald Trump to withhold documents from the congressional committee investigating the Capitol riot.
Mr. Trump had requested that the records sought by the committee be kept secret under executive privilege, which protects some presidential communications.
Meanwhile, his former aide Steve Bannon has vowed to fight a subpoena to testify before the investigation.
The panel has threatened ex-officials with prison if they refuse to cooperate.
Mr Trump’s supporters stormed the Capitol building in Washington on January 6 in an unsuccessful attempt to overturn Mr Biden’s election victory in November.
Hundreds of Mr. Trump’s supporters have since been arrested in connection with their actions that day. Prosecutions are still being pursued.
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The investigating committee requested records relating to the events of the day in August, including communications from Trump, members of his family, top aides, lawyers, and other former members of his administration.
Mr Trump, on the other hand, argued that he could use executive privilege – which allows a president to keep some of their job-related communications private – to keep the documents from being turned over to the investigation.
Former presidents can claim executive privilege, according to legal scholars. The issue is likely to spark a slew of legal challenges that will be decided by the courts.
On Friday, the White House informed the National Archives that Mr. Biden had “determined that an assertion of executive privilege is not in the best interests of the United States.”
In the meantime, Mr. Bannon’s refusal to testify has prompted members of the 6 January committee to threaten him with criminal contempt of Congress charges.
Democrats argue that Mr. Bannon is using a delay tactic to postpone proceedings until after the November 2022 midterm elections, which may change the composition of the House of Representatives, the lower chamber of Congress.
“The whole game is to drag this out as long as possible, to see if they can mobilise enough voter suppression to change hands in Congress,” said Rep Jamie Raskin, adding, “We’re not going to let people play games and sweep evidence under the rug.”
The committee has also called Mark Meadows, Mr. Trump’s former Chief of Staff, Dan Scavino, Mr. Trump’s social media manager, and Kash Patel, a former Pentagon chief of staff, to testify.
Committee leaders Democrat Bennie Thompson and Republican Liz Cheney said in a statement that Mr Meadows and Mr Patel were cooperating with the investigation.
According to US media, Mr. Trump has instructed all four former officials to refuse to cooperate with the investigation.
Mr Trump, who has never admitted he lost the election to Mr Biden, accused Democrats in Congress on Friday of using the committee to “persecute their political opponents.”