House Republican Conference Chair Liz Cheney -- the No. 3 Republican in the House and highest-ranking woman in the Republican Party -- has announced she will vote to impeach Trump for inciting an insurrection at the Capitol.

"Much more will become clear in coming days and weeks, but what we know now is enough," she said in a statement. "The President of the United States 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 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," she said.

Her announcement follows Republican Rep. John Katko of New York becoming the first House Republican to say he will support House Democrats' efforts to remove Trump from office through impeachment.

Republican Rep. John Katko of New York has released a statement saying he will vote to impeach Trump -- becoming the first Republican to publicly voice an expected vote to remove the president from office.

Katko joins at least 218 House Democrats who have signed onto a resolution charging Trump with inciting an insurrection. A House vote could happen as early as Wednesday, one week before Biden's inauguration at the Capitol.

“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 the statement. “For that reason, I cannot sit by without taking action. I will vote to impeach this president."

No House Republicans voted to impeach Trump in 2019.

-ABC News' Benjamin Siegel

The first confirmation hearing for one of Biden's Cabinet picks is officially on the Senate schedule for the day before his inauguration -- which is also the earliest day the Senate is likely to accept an impeachment article against Trump from the House.

Department of Homeland Secretary nominee Alejandro Mayorkas' hearing will be at 10 a.m. on Tuesday, Jan. 19, the Senate Homeland Security and Governmental Affairs Committee announced Tuesday.

In the wake of the siege on the Capitol, the incoming Biden administration is making a push to prioritize confirmations for national security nominees, so those officials may assume their roles as early as next week.

Traditionally, the Senate has confirmed national security nominees on Inauguration Day, and did so for Department of Homeland Security secretary nominees in both 2009 and 2017.

Capitol Police have added new security measures to the House of Representatives -- requiring that all members and staff go through metal detectors before they enter the chamber, according to a new memo sent to offices by the acting House Sergeant at Arms.

The memo comes ahead of a vote Tuesday evening on a resolution pressing Vice President Mike Pence to mobilize the Cabinet and invoke the 25th Amendment to remove Trump from office.

Currently, visitors and staff are screened when they enter the Capitol building, but members of Congress are not. There are already metal detectors in place for visitors to the House galleries, which had been shuttered since March because of the pandemic.

Several lawmakers continue to worry about their safety in the wake of last week's Capitol riot -- and Democrats in control of the chamber have expressed concerns about some GOP colleagues and their alleged connections to the organizers. Some Republicans, most notably Rep. Lauren Boebert, R-Colo. have been outspoken about carrying weapons around the Capitol.

"Failure to complete screening or the carrying of prohibited items could result in denial of access to the Chamber," acting Sergeant at Arms Timothy Blodget wrote in the memo.

-ABC News' Benjamin Siegel and Mariam Khan

In an ongoing House Rules Committee hearing about the resolution to call on Vice President Mike Pence to invoke the 25th Amendment, Democrats are pushing back on GOP Rep. Jim Jordan of Ohio for continuing to suggest the 2020 election should be investigated for fraud.

When Committee Chair James McGovern, D-Mass., asked Jordan if he will concede that the election was not stolen, Jordan repeated Biden was the president-elect but wouldn't say if, in his view, Biden won fairly.

"He won the election because the way the process works is the last chance to object is Jan. 6, and the objection didn't prevail," Jordan said.

"If we want to talk about healing, we have to talk about truth," McGovern interjected in a contentious exchange. "And if we want to talk about healing, we have to deal with the issue of accountability."

Rep. Jamie Raskin, D-Md., who authored the resolution, at one point asked if there's anything Trump could possibly do that would cause Jim Jordan to not defend him.

"Even after a mob of violent insurrectionists staged a gallows outside of the Congress and chanted, 'Hang Mike Pence,' even though they tried to force Mike Pence not to do his job, even after five people are dead, we continue to hear these lies and slurs about the 2020 presidential election," Raskin said.

Rep. Ed Perlmutter, D-Colo, also directly asked Jordan, "Joe Biden won the election, yes or no?"

"Yes, he won. But there are serious problems with this election that deserve an investigation," Jordan said, continuing to air his grievances until Perlmutter interrupted, "I asked you a yes or no question. Please! We're trying to bring this nation back together. Jim, please!"

Jordan, a Trump loyalist, received the Presidential Medal of Freedom from Trump in a closed ceremony at the White House on Monday.