Ahead of Biden's inauguration and in the wake of last week's attack at the Capitol, the United States Capitol Police (USPS) has enhanced security measures across the Capitol Complex, including adding fencing and making several street closures until further notice, the agency announced Thursday.

"Be advised that the U.S. Capitol Complex is closed to the public, and the Capitol Grounds will not be accessible to the public on January 20, 2021.  Anyone attempting to unlawfully gain access to the Capitol Grounds by climbing a fence or any other unlawful means will be subject to an appropriate use of force and arrest," the USPS said in a statement.

Workers were seen installing barbed wire on security fencing surrounding the Capitol on Thursday afternoon as National Guard troops, some armed, patrolled the area. As National Guard troops continue flowing into the area, there are currently over 7,000 currently stationed in Washington with that number expected to grow to 20,000 over the weekend.

-ABC News' Jake Date and Luis Martinez

House Minority Leader Kevin McCarthy, R-Calif., does not support efforts to remove Rep. Liz Cheney, R-Wyo, as House GOP conference chair and a member of House GOP leadership, a McCarthy spokesman told ABC News. This comes after some conservative House Republicans called on her to step down following her announcement that she supported impeaching Trump.

The Wyoming Republican and daughter of former Vice President Dick Cheney is the highest-ranking woman in Republican leadership and was reelected to by GOP members at the start of this Congress.

"We ought to have a second vote," Rep. Jim Jordan, R-Ohio, told reporters Wednesday about the leadership position. "The conference ought to vote on that."

"She should not be serving this conference," Rep. Andy Biggs, R-Arizona, said Tuesday.

On Wednesday night she joined nine other House Republicans in breaking from the party and voting to impeach Trump for his role in last week's riot at the Capitol.

-ABC News' Benjamin Siegel

Republican Sen. Lisa Murkowski of Alaska said in a statement Thursday she believes that the House responded to Trump's actions "appropriately" by impeaching him but does not say how she will vote.

"On the day of the riots, President Trump’s words incited violence, which led to the injury and deaths of Americans – including a Capitol Police officer – the desecration of the Capitol, and briefly interfered with the government’s ability to ensure a peaceful transfer of power. Such unlawful actions cannot go without consequence and the House has responded swiftly, and I believe, appropriately, with impeachment," she said in a statement.

Murkowski said she intends to hear arguments in the Senate before deciding whether she will vote to convict.

"I will follow the oath I made when sworn as a U.S. Senator. I will listen carefully and consider the arguments of both sides, and will then announce how I will vote," Murkowski said.

It's also unclear how Republican Majority Leader Mitch McConnell will vote in the Senate trial, telling Republican colleagues in a memo Wednesday he hasn't "made a final decision" on whether to vote to convict Trump.

-ABC News' Allison Pecorin

Five key Senate panels have now confirmed that they will hold confirmation hearings for Biden's top national security officials before Inauguration Day -- although it remains unlikely most of his picks will be confirmed by day one.

Avril Haines will have her hearing Friday to be Director of National Intelligence, while four others will have theirs on Tuesday -- Tony Blinken for secretary of state, Janet Yellen for Treasury secretary, Lloyd Austin for Defense secretary, and Alejandro Mayorkas for Homeland Security secretary.

The Senate Foreign Relations Committee hasn't scheduled a hearing yet for Linda Thomas-Greenfield, Biden's pick for U.N. ambassador and a member of his Cabinet, despite her being announced in November. Bill Burns, Biden's pick to be CIA director, also doesn't have a hearing scheduled yet, but Biden only announced his intention to nominate Burns Monday.

It's unclear how long after a confirmation hearing any of these Cabinet picks can be confirmed, especially with an impeachment trial -- but they'll require a committee vote and then a full Senate vote. It's likely most won't be confirmed and in position on Inauguration Day.

Biden's team has escalated pressure this week to confirm his national security Cabinet as soon as possible.

In contrast, on Trump's Inauguration Day, the Senate confirmed both John Kelly as Department of Homeland Security secretary and Jim Mattis as Department of Defense secretary, and 11 more Trump nominees already had their confirmation hearings. President Barack Obama had seven Cabinet chiefs confirmed on Inauguration Day, while six more had confirmation hearings by then and his Defense Secretary Bob Gates stayed on from the Bush administration, according to the U.S. Senate website.

-ABC News' Conor Finnegan and Molly Nagle

Addressing the coronavirus pandemic, confronting the climate crisis and building public trust in science and technology will be among the Biden administration's key areas of focus, the president-elect said during a press briefing introducing four key members of his science team.

Building back the economy "to ensure prosperity is fully shared all across America" and ensuring the U.S. "leads the world in technologies and industries that the future" will also be a focus, Biden said Saturday during an address in Wilmington, Delaware.

Helping lead those initiatives will be Eric Lander, the presidential science advisor-designate, a position that for the first time will be a cabinet rank, Biden noted.

"I've always said that the Biden-Harris administration will lead with science and truth," Biden said. "We believe in both. This is how we're going to, God willing, overcome the pandemic and build our country back better than it was before. That's why for the first time in history, I'm going to be elevating the presidential science advisor to a Cabinet rank, because we think it's that important."

Frances Arnold and Maria Zuber will be at the helm of the first all-women team to lead the President’s Council of Advisors on Science and Technology.

Alondra Nelson will also be deputy director for science and society for the Office of Science and Technology Policy.

Dr. Francis Collins, who was not present at the event, will also continue in his role as director of the National Institutes of Health.Biden thanked him for "being willing to stay on," saying that it wasn't his original plan.

"I've known Dr. Collins for many years. I worked with him closely," Biden said, accling him "brilliant, a pioneer, a true leader."

"This is the most exciting announcement that I have gotten to make in the entire Cabinet," Biden said of his picks. "These are among the brightest, most dedicated people, not only in the country but the world."