Hours before a House committee was set to open its investigation into the Jan. 6 Capitol assault, GOP Rep. Liz Cheney shot back at fellow Republicans criticizing her role in the probe, saying, "This is absolutely not a game. This is deadly serious."
Appearing on ABC's "Good Morning America" Tuesday, Cheney lashed out at House GOP Leader Kevin McCarthy.
”There are some in my party, including Leader McCarthy, who continue to act as though this is about partisan politics, I think it's really sad. I think it's a disgrace,” she told ABC’s George Stephanopoulos.
"The American people deserve to know what happened every minute of that day," Cheney said, accusing some Republicans of trying to "whitewash" the assault.
She also said the committee might subpoena McCarthy over what he told then-President Donald Trump as the riot unfolded -- and possibly Trump himself.
On Monday McCarthy kept up his effort to dismiss the probe and attack Cheney and GOP Rep. Adam Kinzinger -- who've agreed to serve with Democrats.
ABC News Special
The detailed timeline of events surrounding the deadly siege of the U.S. Capitol and violence in Washington, D.C. on January 6, 2021.
When asked on Monday if he'll punish Cheney of Wyoming and Kinzinger of Illinois -- McCarthy said "we'll see," amid speculation their fellow Republicans might try to remove them from House committee assignments for accepting House Speaker Nancy Pelosi's invitation.
Speaking with reporters at a bipartisan White House even celebrating the Americans with Disabilities Act, McCarthy called them "Pelosi Republicans."
"Couldn't tell you," he said, when asked the last time he spoke to Cheney and Kinzinger.
When asked for his take on the first witnesses -- law enforcement officers who defended the Capitol against the pro-Trump mob -- McCarthy replied, "I don't know."
Then Monday evening, House Republicans attempted to pass a privileged resolution on the floor to condemn Pelosi for refusing to seat all of McCarthy's Republican lawmakers on the committee. It also urged Pelosi to appoint those she'd refused: Reps. Jim Jordan of Ohio and Jim Banks of Indiana. The House quickly voted 218-197 to table the surprise resolution, effectively killing it.
Earlier Monday on Capitol Hill, Cheney shot back at McCarthy.
"We've got very serious business here. We have important work to do. And I think that's pretty childish," she told reporters.
Kinzinger on Monday slammed other Republicans in response to McCarthy's dig.
"If the conference decides, or if Kevin decides they want to punish Liz Cheney and I for getting into the bottom and telling the truth, I think that probably says more about them than it does for us," he said.
Kinzinger added his preference was the independent commission negotiated and then blocked by GOP leaders.
"It's become obvious that there are some that just simply don't want answers, and that to me is unacceptable," he told reporters.
Earlier Monday, committee members checked out the Cannon Office Building hearing room ahead of Tuesday's start at 9:30 a.m.
Chairman Bennie Thompson, D-Miss., and Cheney will each deliver opening statements in Tuesday's hearing before the police officers testify, according to a congressional aide. The committee will hear from Capitol Police officers Harry Dunn and Aquilino Gonell and Michael Fanone and Daniel Hodges of the Metropolitan Police Department.
Normally, the ranking member -- or top Republican -- would be given an opportunity to make opening remarks after the committee chair speaks. But Republican leaders have pulled their members from the panel, leaving Cheney and Kinzinger as the only GOP members.
Cheney and Kinzinger are the only two House Republicans who voted to form a select committee after Senate Republicans killed a proposal for a bipartisan, independent commission. Like Cheney, Kinzinger is among the 10 Republicans to vote to impeach Trump for "incitement of insurrection."
Tuesday's hearing is expected to go two to three hours and will feature video elements, according to an aide.
McCarthy had vowed that his GOP appointments wouldn't participate after Pelosi rejected Banks and Jordan, citing statements made and actions taken, she said, would threaten the credibility of the committee.
White House press secretary Jen Psaki said at a briefing Monday that President Joe Biden will be "kept abreast" of Tuesday's committee hearing.
"In his view, in our view, tomorrow's hearing will be an opportunity to hear firsthand from the men and women in the Capitol Police and the Metropolitan Police Department who bravely protected our Capitol on that day. His goal is the same goal that Speaker Pelosi has, which is to get to the bottom of what happened and prevent it from happening in the future, and he trusts her leadership to do exactly that," she said.
Dunn, one of the police officers who is scheduled to testify Tuesday, tweeted out Monday asking for "good vibes."
Mark Zaid, the whistleblower attorney who is also representing Dunn, late last week posted this Twitter thread flagging that after Fox News host Tucker Carlson attacked Dunn on his show as an "angry left-wing political activist" he received "numerous vile/racist" messages, with some citing Carlson's comments.
Fanone, an officer with the Metropolitan Police Department who was brutally attacked by rioters on Jan. 6, video shows, told ABC News Congressional Correspondent Rachel Scott that he plans to testify in uniform Tuesday and said he won't let politics hinder his appearance.
"I don't get care what the vehicle is -- as long as the truth comes out," he said, when asked about Republicans who are throwing cold water on the committee. Fanone was at the Capitol Monday to prepare for the hearing.
He added that he supports any investigation that is looking for a "factual account" of what happened that day.
Back in May, Fanone and Dunn escorted the family of fallen Capitol Police officer Brian Sicknick door-to-door on Capitol Hill pleading with Republicans for an independent commission.
Rep. Adam Schiff, D-Calif., a member of the panel and chairman of the House Intelligence Committee, who briefed reporters ahead of the hearing, said there will be a mix of old and new video footage shown Tuesday.
Asked why they're starting with these witnesses, Schiff said they can "explain what took place and what we're seeing in these clips and also put to rest some of the revisionist history, the effort to whitewash what took place and understand keenly the importance of getting to the truth about what led up to that insurrection and what happened thereafter."
"We really want to hear from the officers and the videos are designed to have them explain what they saw and what they confronted," he said.
ABC News' Justin Gomez contributed to this report.