Congressional Democratic leaders commended Biden's announcement outlining his COVID-19 emergency relief proposal.

"The emergency relief framework announced by the incoming Biden-Harris Administration tonight is the right approach. It shows that Democrats will finally have a partner at the White House that understands the need to take swift action to address the needs of struggling communities," House Speaker Nancy Pelosi and Senate Minority Leader Chuck Schumer said in a statement.

"We will get right to work to turn President-elect Biden's vision into legislation that will pass both chambers and be signed into law," they added.

"The robust package announced by President-elect Biden and Vice President-elect Harris shows we now have the necessary leadership in the Executive Branch to turn this around and we are ready to get to work to deliver aid without delay," Pelosi and Schumer said.

-ABC News' Mariam Khan

Biden will propose a $1.9 trillion, “American Rescue Plan" to address the ongoing COVID-19 vaccination effort and immediate economic need to Americans in evening remarks, transition officials disclosed on a call with reporters Thursday.

According to officials on the call, the rescue policy is only one part of Biden’s overall policy, with a “recovery” phase expected to be introduced in February. They said Biden’s rescue policy will include three components: Tackling vaccine distribution, ramping up testing and getting kids back in school within the first 100 days of his administration; delivering $1,400 per-person direct stimulus checks and expanding unemployment benefits, including $400 weekly benefit through September on top of state benefits; and delivering aid to states and communities to support small businesses, addressing housing insecurity by expanding the eviction and foreclosure moratorium through Sept. 2021.

More than $1 trillion of the $1.9 trillion price tag will be used for direct stimulus, officials said, while $400 billion will go toward COVID-19-related projects, including the nationwide vaccination program, and $440 billion will go toward relief for communities and businesses.

Biden will also call for Congress to provide $350 billion for state local and territorial governments, an effort to keep essential workers on the job.

If enacted, it would be one of the largest and most expensive economic stimulus packages in U.S. history.

-ABC News Molly Nagle, John Verhovek, Beatrice Peterson and Averi Harper

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

House Democrats have opened an investigation into what law enforcement and the intelligence community knew about threats to the Capitol ahead of the Jan. 6 siege.

The investigation from the House Intelligence, Oversight, Homeland Security and Judiciary committees will also examine whether anyone with security clearances -- current or former National Security, Defense, Justice or Homeland Security officials -- participated in the riot.

The investigation will also examine the federal law enforcement response in the aftermath of the attack.

"The Committees will conduct robust oversight to understand what warning signs may have been missed, determine whether there were systemic failures, and consider how to best address countering domestic violent extremism, including remedying any gaps in legislation or policy," committee members wrote in a letter to the FBI, DHS and Office of the Director of National Intelligence.

"This still-emerging story is one of astounding bravery by some U.S. Capitol Police and other officers; of staggering treachery by violent criminals; and of apparent and high-level failures -- in particular, with respect to intelligence and security preparedness," the letter later stated.

Democrats plan to request documents and briefings from administration officials as part of the investigation -- just one of several looking into the Capitol attack.

-ABC News' Benjamin Siegel