Bennie Thompson, the chairman of the House select committee investigating the Capitol attack on Thursday announced the panel’s intention to consider a criminal contempt referral against Trump’s former strategist Steve Bannon for defying a subpoena as part of its 6 January inquiry.

The vow to initiate contempt of Congress proceedings against Bannon – one of Donald Trump’s top advisers – puts the select committee on the path to enforce the subpoena issued to uncover what the former president knew in advance of plans to mount an insurrection.

Thompson said in a statement that the committee would move to consider prosecuting Bannon for refusing to comply with a subpoena demanding documents and testimony after rejecting his claims that he could not appear for a deposition because of executive privilege.

“The select committee will not tolerate defiance of our subpoenas, so we must move forward with proceedings to refer Mr Bannon for criminal contempt,” Thompson said. “Witnesses who try to stonewall the select committee will not succeed.”

The select committee will meet on Tuesday to decide whether to recommend the full House authorize a criminal referral for Bannon to the justice department, Thompson said, though with the panel’s members united in their fury, the decision is expected to be unanimous.

House select committee investigators had ordered Bannon and Kash Patel, a former Trump defense department aide, to testify on Thursday, with additional closed-door interviews with Trump’s former White House chief of staff Mark Meadows and his deputy, Dan Scavino, on Friday.

Neither Bannon nor Patel ultimately appeared on Capitol Hill for the first set of scheduled depositions, after Trump instructed his aides to defy the subpoenas on grounds that any discussions that involved him were protected by executive privilege.

The select committee temporarily postponed depositions with Patel and Meadows while their lawyers continued to discuss cooperation, according to a source familiar with the matter. Scavino was also granted a reprieve after having his subpoena served late.

But Thompson made clear that he had run out of patience with Bannon, who twice told the select committee that he intended to defy his subpoena in its entirety, abiding by the former president’s instructions first reported by the Guardian.

“Mr Bannon has declined to cooperate with the select committee, and is instead hiding behind the former president’s insufficient, blanket, and vague statements regarding privileges,” Thompson said. “We reject his position entirely.”

The select committee chairman also rejected Bannon’s executive privilege claim, in part because the protection exists to protect the interests of the country, and not the private, political interests of a former president, the source said.

Once the select committee adopts a contempt report, it is referred to the full House for a vote. Should the House approve the report, Congress can then send the request for a criminal referral to the US attorney for the District of Columbia.

The earliest the select committee can vote to adopt a contempt report for Bannon is Tuesday, because House rules require Thompson to issue a three-day notice in advance of a business meeting at which members can discharge the report.

Congresswoman Stephanie Murphy, a member of the select committee, said on MSNBC that the panel was moving to enforce the subpoenas as soon as it could. “I fully expect this Department of Justice to uphold and enforce that subpoena,” she added.

House select committee investigators had expressed optimism when they first issued subpoenas to the four Trump administration officials that they would be able to hear from at least one of their marquee witnesses on the scheduled deposition dates.

Yet the initial optimism rapidly turned sour in the weeks that followed, after Trump announced his intention to block the select committee at every turn and the prospects of deposing some of the closest aides to the former president vanished before their eyes.

The move to consider launching a criminal referral for Bannon to the justice department sets up a potentially lengthy legal battle that is certain to test Congress’s oversight authority over the executive branch and ability to uncover presidential secrets.

And in preparing for the first step to hold Bannon in contempt of Congress, the select committee now faces the prospect of fighting Trump in court on two fronts – over the release of White House records, as well as his power to block his aides’ testimony.

The former president, however, faces a steep uphill struggle in both instances after the justice department previously authorized officials from the Trump administration to testify to Congress about the Capitol attack and Trump’s efforts to subvert the 2020 election.