House Republican Conference Chair Liz Cheney speaks at a news conference on Capitol Hill in Washington, May 8, 2019.Aaron P. Bernstein | ReutersRep. Liz Cheney, the third-ranking House Republican, said Tuesday she will vote to impeach President Donald Trump, becoming the second GOP lawmaker to take the step.She is the highest-ranking Republican to call for the president’s impeachment in the wake of Wednesday’s deadly Capitol Hill riot, which Trump helped incite with lies and incendiary rhetoric.Rep. John Katko, R-N.Y., earlier said he would support impeachment after the president stirred up a mob that attacked the Capitol last week while Congress counted President-elect Joe Biden’s presidential win.In a statement, Cheney said Trump “summoned this mob, assembled the mob and lit the flame of this attack.””Everything that followed was his doing. None of this would have happened without the President,” the Republican conference chair said. “The President could have immediately and forcefully intervened to stop the violence. He did not. There has never been a greater betrayal by a President of the United States of his office and his oath to the Constitution.”The House plans to vote Wednesday on whether to charge Trump with high crimes and misdemeanors. Democrats have said they have enough votes to impeach the president for an unprecedented second time.More Republicans could join Cheney and Katko in backing the effort.Cheney, a Wyoming Republican, breaks from House Minority Leader Kevin McCarthy. The California Republican has opposed impeaching Trump.The lawmakers revealed their stances as the New York Times reported that Senate Majority Leader Mitch McConnell, R-Ky., has told associates he thinks Trump committed impeachable acts. The newspaper did not detail whether McConnell would vote to convict the president if the House sends articles of impeachment to the Senate, or whether he would urge Republicans to vote the same way.Trump earlier said Democrats’ push to impeach him was dangerous and could spark more violence.This story is developing. Please check back for updates.Subscribe to CNBC on YouTube.