Donald Trump’s former attorney Rudy Giuliani is not expected to appear at an interview scheduled for Friday with the House select committee investigating the January 6 Capitol attack, throwing into jeopardy the prospect of his cooperation, say sources familiar with the matter.

The move by Giuliani to cancel his appearance after the panel declined his request to record the interview means it may not secure documents and testimony from a central figure in Trump’s efforts to overturn the 2020 election in time for public hearings in June.

Giuliani was expected to have revealed his contacts with Republican members of Congress and other matters not covered by executive privilege or attorney-client privilege as part of a cooperation deal that his lawyer had been negotiating for months, the sources said.

The former attorney to the president had also indicated to the select committee that he was prepared to turn over materials about Trump’s schemes to return himself to office on January 6 that House investigators had outlined in a subpoena issued earlier this year.

But, as the Guardian first reported in February, Giuliani told the panel he would only appear for an interview if it was not pursuant to that subpoena – in part because he considered the investigation illegal – and does not have to violate any claims of privilege.

The select committee has conceded that Giuliani cannot violate privilege, the sources said, making a deal attractive to Giuliani, who can avoid being held in contempt of Congress by providing information the panel could not otherwise get – while also not giving up Trump.

But that delicate arrangement appeared to fall apart on Thursday, after Giuliani also asked to record the interview to ensure he might not be caught in a perjury trap in a potential subsequent investigation, according to another source close to Giuliani.

The no-show by Giuliani could also presage the breakdown of the entire cooperation deal, the source said, and Giuliani is expected to wait for the panel’s response to decide next steps. Giuliani may reschedule the interview if the impasse is resolved.

“Giuliani is an important witness to the conspiracy to overthrow the government and he remains under subpoena,” a spokesperson for the select committee said. “If he refuses to comply, the committee will consider all enforcement options.”

House investigators have been particularly determined to get the cooperation from Giuliani, one of Trump’s closest advisers involved in efforts to overturn the 2020 election from the very start – and could provide unique insights into the events of January 6.

Giuliani could speak to events such as a 18 December 2020 meeting in the Oval Office where Trump reviewed a draft executive order to seize voting machines and verbally agreed to install conspiracy theorist Sidney Powell as special counsel to investigate election fraud.

The Guardian has reported that Giuliani then led the Trump “war room” at the Willard hotel in Washington DC when Trump called from the White House and discussed ways to stop Biden’s certification – and could speak to non-privileged elements of the plan.

The cooperation deal would also technically involve Giuliani turning over documents in addition to appearing before the select committee, the sources said, but the logistics were unclear given the FBI last year seized his devices that he used on January 6.