House GOP Conference Chairwoman Liz Cheney of Wyoming and Rep. John Katko of New York are planning to support Democrats' effort to impeach President Trump after last week's riots at the U.S. Capitol, Fox News has confirmed.

"To allow the president of the United States to incite this attack without consequence is a direct threat to the future of our democracy," Katko said in a statement released Tuesday. "For that reason, I cannot sit by without taking action. I will vote to impeach this president."

After Cheney's and Katko's announcement, Rep. Adam Kinzinger, R-Ill., later tweeted a statement backing impeachment. "We are in unchartered waters here, and in history we have not experienced in modern times," he said. He added that "there is no doubt in my mind that the President of the United States broke his oath of office and incited this insurrection."

Democrats' impeachment resolution accuses Trump of inciting an insurrection and supports disqualifying him from holding future office.

A senior administration official told Fox News the White House is expecting anywhere between 10 and 20 Republicans to vote in favor of moving ahead with impeachment. The official said the number could possibly go above 20, though they doubted that.

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Cheney blasted Trump in a statement, saying, "Much more will become clear in coming days and weeks, but what we know now is enough.

"The President of the United States summoned this mob, assembled the mob, and lit the flame of this attack," she said. "Everything that followed was his doing. None of this would have happened without the President. 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. I will vote to impeach the President." 

The news came as the president faced heightened scrutiny from his own party. The New York Times previously reported Republican Senate Majority Leader Mitch McConnell was "pleased" with the pending impeachment vote, while House Minority Leader Kevin McCarthy, R-Calif., has been asking members about potentially backing the measure.

A source close to McConnell told Fox News that he was furious with Trump. "He's done with Trump," a source said. It’s unclear, though, whether McConnell will ultimately vote to remove the president in a Senate trial. A source very close to McConnell also disputed the Times' reporting, saying that nobody was "pleased" by anything. 

Although McCarthy has told colleagues he opposes impeachment, House Republican leadership told Fox News that the party wouldn't be lobbying members to oppose Trump's impeachment.

The call for impeachment has encountered resistance from other Republicans, including Sen. Roy Blunt of Missouri, who panned the idea on Friday. "There is no way we're going to impeach the president. There's not the time to do it," said Blunt.

He described the effort as "just another political point trying to be made. It's disappointing. It'd be much more disappointing if people can't through see that."

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Democratic leaders have called for Trump's swift removal from office, arguing that he poses a threat to American democracy with less than two weeks before President-elect Biden is inaugurated. Impeachment has also been viewed as a way to keep Trump from holding future office.

A vote on the articles is expected on Wednesday, exactly a week after the riots that involved violent confrontations with Capitol police. At least one officer has died in relation to the riots while another committed suicide after they occurred. 

Fox News' John Roberts and Mike Emanuel contributed to this report.