Rep Liz Cheney accused House Minority Leader Kevin McCarthy of trying to cover up what happened during the insurrection at the Capitol on 6 January of last year.
Ms Cheney, who serves as the vice chairwoman of the select committee investigating the riot, made the remarks to CNN after Mr McCarthy rebuffed a request by the committee to provide information.
“As a representative and the leader of the minority party, it is with neither regret nor satisfaction that I have concluded to not participate with this select committee's abuse of power that stains this institution today and will harm it going forward,” Mr McCarthy said in a statement.
Mr McCarthy specifically also complained about the fact House Speaker Nancy Pelosi refused to seat two of his choices--Reps Jim Jordan and Ohio and Jim Banks of Indiana, both of whom are allies of former president Donald Trump--on the select committee.
But Ms Cheney criticised Mr McCarthy’s refusal to provide information.
“I wish that he were a brave and honorable man,” Ms Cheney told CNN. “He's clearly trying to cover up what happened. He has an obligation to come forward and we'll get to the truth.”
Ms Cheney and Mr McCarthy have had a contentious relationship since last year. Ms Cheney, the daughter of former vice president Dick Cheney, led the House Republican Conference and was seen as a potential future Speaker of the House and the first female Republican Speaker.
But her vote to impeach Mr Trump for his actions on January 6 followed by her repeated criticisms of the GOP for being married to lies about the election being stolen led to Mr McCarthy and the rest of House of the House GOP caucus ousting her from the position.
Since then, Ms Pelosi selected her to sit on the select committee. After Mr McCarthy pulled all of his selections in response to Ms Pelosi refusing to seat Mr Banks and Mr Jordan, Rep Adam Kinzinger of Illinois joined the committee and is the only other Republican on the committee.
The select committee specifically is requesting Mr McCarthy provide information about his communications with the former president before, during and after the attack on the Capitol.
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