Members of the US Congress voted on Thursday to hold Steve Bannon, a key ally of former president Donald Trump, in criminal contempt for defying a subpoena to appear before a panel investigating the January 6 attack on the Capitol.
The former White House chief strategist has been in the spotlight over the role he may have had in organising the insurrection and any efforts he may have pursued to co-ordinate with Mr Trump and the White House.
All 220 Democrats backed the resolution to hold Mr Bannon in criminal contempt of Congress.
Nine rebel Republicans, including January 6 committee members Adam Kinzinger and Liz Cheney, the vice chairwoman and the most prominent anti-Trump voice in her party, backed it as well.
Ms Cheney, who earlier this year was ousted as the third-ranking Republican in the House for voting to impeach Mr Trump, said Mr Bannon's own public statements leading up to the attack on the Capitol indicate he knew what was going to happen.
Mr Bannon "said all hell is going to break loose. He said, 'We are coming in right over the target,'" Ms Cheney said during debate ahead of the vote.
"There is no doubt that Mr Bannon knows far more... There is no doubt that all hell did break loose."
"The American people deserve to know what he knew and what he did," she added.
Mr Bannon is now expected to be referred to federal prosecutors, but the ensuing legal battle could play out over months or even years, potentially frustrating the probe.
Attorney General Merrick Garland, at a hearing before the House Judiciary Committee ahead of the vote, said the Justice Department will follow “the facts and law” in handling the contempt referral on Bannon.
Members of Congress “take an oath to protect and defend the Constitution of the United States. The genius of our constitution and of our founders was the separation of power — checks and balances,” House Speaker Nancy Pelosi told reporters on Thursday.
Investigators see Mr Bannon's evidence as pivotal to gaining a clear understanding of Mr Trump's actions before and during the deadly assault on a joint session of Congress to certify Joe Biden's election victory.
“According to published reports, Bannon had specific knowledge about the events of January 6 before they occurred, and had multiple roles relevant to the attack, and [was] very outspoken about it,” Ms Pelosi told reporters before the vote.
Mr Bannon, 67, was supposed to appear before the cross-party congressional select committee last week but said Mr Trump's lawyers had instructed him not to show up on the grounds of “executive privilege”, which allows presidents to keep certain communications with aides confidential.
The January 6 committee says that protection does not apply, as Mr Trump is out of office and has never formally asserted the privilege.
Mr Bannon, they point out, was not even a government employee during the period covered by the subpoena.
Mr Trump has continued to insist falsely that his defeat was the result of fraud. Multiple courts, state election officials and members of Trump's own administration have rejected his lies.
On Thursday Mr Trump released a statement falsely claiming that the "insurrection took place on November 3. Election Day. January 6 was the protest," he said.
Four people died on the day of the assault on the US Capitol. Hundreds of police officers were injured and four have since taken their own lives.
Agencies contributed to this report