The House Jan. 6 panel is scheduled to interview Pompeo and Mastriano on Tuesday.

In the wake of the F.B.I. search of former President Donald J. Trump’s property in Florida, the House committee investigating the Jan. 6 attack on the Capitol is gearing up to meet with two potentially key witnesses in its separate inquiry on Tuesday.

The committee is expected to meet with Mike Pompeo, the former secretary of state under Mr. Trump, and Douglas V. Mastriano, the Republican nominee for governor of Pennsylvania who served as a point person in the state for a plan to keep Mr. Trump in power by using slates of “alternative” or “fake” electors.

Mr. Pompeo has been in talks with the committee about his appearance for weeks, according to a person familiar with the matter, and could provide testimony about discussions within Mr. Trump’s cabinet about the possibility of invoking the 25th Amendment to remove Mr. Trump from office after the events of Jan. 6, 2021.

Mr. Pompeo’s discussion regarding the 25th Amendment was reported by Jonathan Karl of ABC News in his book “Betrayal.”

A spokesman for the Jan. 6 committee declined to comment. A spokesman for Mr. Pompeo did not respond to a request for comment.

Tuesday’s virtual interview with Mr. Mastriano is expected to be short, because he plans to object to the panel’s rules about video recording. A lawyer for Mr. Mastriano, currently a state senator, said Mr. Mastriano believed the committee would selectively edit his testimony, and planned to insist on making his own video recording of the interview. The committee has rejected that option for other witnesses, including Rudolph W. Giuliani, Mr. Trump’s personal lawyer.

“Senator Mastriano has nothing to hide and would be happy to answer their questions. Our only concern is to prevent the committee from releasing misleading and edited portions while keeping the proper context hidden. Either release the entirety or let me make a copy and we have no issue,” Timothy C. Parlatore, Mr. Mastriano’s lawyer, said in a text message. “Unfortunately the committee has refused to discuss any arrangements other than to demand that they be allowed to exclusively control what portions can be released.”

It is unclear what the committee’s response will be if Mr. Mastriano ends the interview abruptly.

Mr. Mastriano, a former Army officer, was on the Capitol grounds on Jan. 6, though he later explained in a statement that “he followed the directions of the Capitol Police and respected all police lines” that day. The committee has said it wants to interview Mr. Mastriano because he spoke directly with Mr. Trump about his “postelection activities.”

Emails reviewed by The New York Times also show that Mr. Mastriano served as a point person for the Trump campaign as it assembled groups of pro-Trump electors in states won by President Biden. The emails showed Mr. Mastriano needed assurances to go along with the plan because other Republicans had told him it was “illegal.”

Mr. Mastriano has turned over documents to the Jan. 6 committee that included information about busing people to Washington for a large rally that preceded the violence, and copies of posts he made on social media.