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

Incoming White House Chief of Staff Ron Klain gave an overview of the first 10 days of the Biden-Harris administration in a memo to senior staff Saturday shared with reporters.

"President-elect Biden is assuming the presidency in a moment of profound crisis for our nation. We face four overlapping and compounding crises: the COVID-19 crisis, the resulting economic crisis, the climate crisis, and a racial equity crisis. All of these crises demand urgent action," Klain wrote. "In his first 10 days in office, President-elect Biden will take decisive action to address these four crises, prevent other urgent and irreversible harms, and restore America’s place in the world."

The schedule is not comprehensive, Klain noted, but includes:

Jan. 20: Biden plans to ask the Department of Education to extend the pause on student loan payments and interest for Americans with federal student loans, rejoin the Paris Agreement, reverse the "Muslim Ban" (one of Trump's earliest executive orders upon taking office) and issue a mask mandate for federal property and inter-state travel. He will also "take action to extend nationwide restrictions on evictions and foreclosures and provide more than 25 million Americans greater stability."

Jan. 21: Biden plans to sign several executive actions "to move aggressively to change the course of the COVID-19 crisis and safely re-open schools and businesses, including by taking action to mitigate spread through expanding testing, protecting workers, and establishing clear public health standards."

Jan. 22: The president-elect will direct his Cabinet agencies "to take immediate action to deliver economic relief to working families" impacted by the pandemic.

Jan. 25-Feb. 1: Among other executive actions, memoranda and Cabinet directives, Biden plans to sign additional executive actions to address the climate crisis, as well as take steps to "strengthen Buy American provisions," reform the criminal justice system, expand health care access and "start the difficult but critical work of reuniting families separated at the border."

"Full achievement of the Biden-Harris Administration’s policy objectives requires not just the executive actions the president-elect has promised to take, but also robust Congressional action," Klain wrote.

-ABC News' John Verhovek