Republican leader Kevin McCarthy’s refusal to provide information to a bipartisan House committee about his call with then-President Donald Trump during the Capitol riot is deepening a standoff between the committee and GOP lawmakers, forcing investigators to consider whether they could subpoena one of their own.

McCarthy joined two other Trump allies, Reps. Jim Jordan of Ohio and Scott Perry of Pennsylvania, in rejecting the panel’s requests for interviews and documents. McCarthy, R-Calif., decried the committee as an “abuse of power” and said he had little to offer.

There is “nothing that I can provide” to the committee, he said, as it investigates what Trump was doing inside the White House, and his state of mind, as hundreds of his supporters violently pushed past law enforcement in an insurrection that temporarily halted the congressional certification of Democrat Joe Biden’s White House win.

The stand by the three GOP lawmakers has left the committee of seven Democrats and two Republicans with a stark choice: take the extraordinary step of subpoenaing their own colleagues or allow the requests, and the defiance of their work, to go unanswered.

The committee’s leaders, Chairman Bennie Thompson, D-Miss., and Vice Chairwoman Liz Cheney, R-Wyo., have said they are prepared to subpoena any witness crucial to the investigation. But privately, committee members are wrestling over the potential legal and political complications of such a move. While congressional ethics committees have the authority to subpoena lawmakers, there is little modern precedent for another committee doing so.

In a December interview with The Associated Press, Thompson said there is uncertainty over whether such a subpoena could be enforced because of the speech and debate clause of the Constitution, which says members of Congress “shall not be questioned in any other place” for their words in either House.

“I doubt it, because of the speech and debate clause,” Thompson said. “There is no precedent to force that compliance.”

Still, the committee has not ruled it out. The committee has publicly subpoenaed about 50 other witnesses and many others privately.

McCarthy has acknowledged the call with Trump on Jan. 6, 2021, which happened as Trump’s supporters were beating police outside the Capitol and forcing their way into the building. But McCarthy has not shared many details. The committee requested information about his conversations with Trump “before, during and after” the riot.

McCarthy took to the House floor after the rioters were cleared and said in a forceful speech that Trump “bears responsibility” for the attack and that it was the “saddest day I have ever had” in Congress — even as he went on to join 138 other House Republicans in voting to reject the election results. McCarthy soon made up with Trump, though, visiting him in Florida and rallying House Republicans to vote against investigations of the attack.

At Trump’s second impeachment trial, just after the insurrection, Democrats said they would try and call Rep. Jaime Herrera Beutler, R-Wash., as a witness. She had described McCarthy’s call with Trump after hearing an account of it from McCarthy.

McCarthy told Trump to publicly “call off the riot” and said the violent mob was made up of Trump supporters, not far-left antifa members, as Trump had claimed, according to a statement from Herrera Beutler.

“That’s when, according to McCarthy, the president said, ‘Well, Kevin, I guess these people are more upset about the election than you are.,” Herrera Beutler’s statement said.

In the end, Democrats read a statement from Herrera Beutler into the record. Trump, who had just left office, was acquitted by the Senate of inciting the insurrection.

Speaking to reporters Thursday, McCarthy said the conversation with Trump “was very short, advising the president what was happening here.”

The committee’s request also seeks information about McCarthy’s communications with then-White House chief of staff Mark Meadows and communications with Trump and White House staff in the week after the violence, including reports of a conversation that was “heated.”

In Wednesday’s letter, Thompson said the committee “must learn about how the President’s plans for January 6th came together, and all the other ways he attempted to alter the results of the election. For example, in advance of January 6th, you reportedly explained to Mark Meadows and the former President that objections to the certification of the electoral votes on January 6th ‘was doomed to fail.’”

The committee acknowledged the sensitive and unusual nature of its request as it proposed a meeting with McCarthy on either Feb. 3 or 4. “The Select Committee has tremendous respect for the prerogatives of Congress and the privacy of its Members,” Thompson wrote. “At the same time, we have a solemn responsibility to investigate fully the facts and circumstances of these events.”

Despite the resistance of some high-profile Trump allies, the Jan. 6 committee has interviewed almost 350 people as it seeks to create a comprehensive record of the attack and the events leading up to it.

On Wednesday, former White House Press Secretary Kayleigh McEnany spoke virtually to the committee, according to a person familiar with the interview who was not authorized to discuss it publicly. The committee subpoenaed McEnany in November.