The former Trump White House chief of staff Mark Meadows will testify before the House select committee investigating the Capitol attack as part of an initial cooperation agreement reached with his lawyer, the panel’s chairman, Bennie Thompson, announced on Tuesday.

The agreement involves Meadows appearing for a deposition and providing documents that are not protected by executive privilege. The move is aimed at staving off the threat of criminal prosecution for defying a subpoena in its entirety.

“Meadows has been engaging with the select committee,” Thompson said. “He has produced records to the committee and will soon appear for an initial deposition. The committee will continue to assess his degree of compliance with our subpoena after the deposition.”

The select committee is seeking to hear from Meadows since his role as White House chief of staff means he may hold the key to unlocking the extent of Trump’s involvement in efforts to stop the congressional certification of Joe Biden’s election victory.

The select committee also believes that Meadows remained by Trump’s side for most of 6 January and was therefore in a unique position to know what the former president was privately thinking and doing at the White House as the deadly attack on the Capitol unfolded.

But after Trump directed his former aides to defy subpoenas issued by the select committee on grounds of executive privilege, Meadows refused to appear for depositions or turn over materials while he negotiated the scope of his cooperation with the committee.

That left Meadows vulnerable to criminal prosecution for defying his subpoena first issued in September, but Thompson said in a statement on Tuesday that the select committee had at least tentatively resolved that impasse.

Still, the agreement is understood to be delicate and Thompson appeared to suggest that Meadows still risked facing contempt of Congress charges alongside the former Trump adviser Steve Bannon and Trump Department of Justice official Jeffrey Clark, if he violated the deal.

As part of the deposition arrangement, the select committee did not agree to take any topics for questioning off the table. Meadows also retains the ability to invoke executive privilege and refuse to respond over the course of his testimony.

“As we have from the beginning, we continue to work with the select committee and its staff to see if we can reach an accommodation that does not require Mr Meadows to waive executive privilege,” Meadows’s attorney George Terwilliger said in a statement.

The acknowledgment of the agreement, first reported by CNN, means the select committee may depose its first Trump White House aide before the end of the year after struggling to compel the cooperation of any other top Trump administration official.

The select committee is expected to vote unanimously on Wednesday to hold Clark, the former Trump DoJ official, in contempt of Congress after he ignored a subpoena demanding documents and testimony in its entirety, citing vague claims of attorney-client privilege.

The full House of Representatives earlier referred Bannon, Trump’s former adviser, to the justice department for prosecution after he also defied a subpoena. Bannon pleaded not guilty to two contempt of Congress charges and is expected to fight his indictment.