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

Late Friday, Health and Human Services Secretary Alex Azar refuted several media reports that he was resigning early, but did share his resignation letter -- effective Jan. 20 at noon -- on Twitter.

While Azar wrote on Twitter that it was his "duty to help ensure a smooth transition to President-elect Biden’s team during the pandemic" through Inauguration Day, he did criticize President Donald Trump and called on him to more strongly condemn the violence at the Capitol last week.

"Unfortunately, the actions and rhetoric following the election, especially during this past week, threaten to tarnish these and other historic legacies of this Administration," Azar wrote in the resignation letter. "The attacks on the Capitol were an assault on our democracy and on the tradition of peaceful transitions of power that the United States of America first brought to the world. I implore you to continue to condemn unequivocally any form of violence, to demand that no one attempt to disrupt the inaugural activities in Washington or elsewhere, and to continue to support unreservedly the peaceful and orderly transition of power on January 20, 2021."

Azar clarified he handed in the letter, dated Jan. 12, last week "along with every other political appointee."

The two-page letter, in which he calls serving as HHS secretary "the greatest professional privilege and honor of my life," details the administration's response to the coronavirus pandemic. Azar paints an entirely rosy picture, referring to it as a "remarkable response," despite skyrocketing deaths and case rates across most of the nation.

"While we mourn every lost life, our early, aggressive, and comprehensive efforts saved hundreds of thousands or even millions of American lives," he wrote, echoing a refrain from the president. There have been over 391,000 deaths in the U.S., nearly twice the number of the second-highest country (208,000 in Brazil).

He also highlighted the agency's efforts to combat the opioid crisis, electronic cigarettes and the HIV epidemic, and made special mention of "protect[ing] the sanctity of human life from conception to natural death."

Azar has served as HHS secretary since January 2018. President-elect Joe Biden has nominated Xavier Becerra, California's attorney general, to serve as his HHS chief.

ABC News' Ben Siu contributed to this report.