Biden, in an evening address from Wilmington, Delaware, is announcing his vaccination and economic rescue legislative package.

The ambitious $1.9 trillion proposal focuses on stimulus amid the ongoing pandemic.

Biden's plan would dedicate more than $1 trillion of the $1.9 trillion price tag for direct stimulus, officials said, while $400 billion would go toward COVID-related projects, including the nationwide vaccination program, and $440 billion toward relief for communities and businesses.

The plan includes direct payments of up to $1,400 to families in need, that when combined with the recent $600 stimulus payment would deliver on Biden's pledge to pass $2,000 of direct payments, along with a $400 weekly unemployment insurance benefit through September and a child tax credit.

-ABC News' Molly Nagle

Photos show the beginning of the process to move President Donald Trump out of the White House, as workers load boxes on to trucks.

Biden on Thursday announced his slate for new leadership at the Democratic National Committee, including former South Carolina U.S. Senate candidate Jaime Harrison to be the next chair of the DNC.

Harrison, who lost the 2020 race to GOP Sen. Lindsey Graham last year, despite breaking numerous fundraising records, will officially become DNC chair after the full committee votes on Jan. 21, the day after Biden's inauguration.

Graham congratulated Harrison on the news in a tweet earlier Thursday.

In addition to Harrison, Biden also announced the names of four DNC vice chairs, all of whom were prominent backers of his presidential campaign, including Michigan Gov. Gretchen Whitmer, who served as a campaign co-chair.

Whitmer is joined by Atlanta Mayor Keisha Lance Bottoms, Illinois Sen. Tammy Duckworth and Texas Rep. Filemon Vela as new DNC vice chairs.

House Speaker Nancy Pelosi called Harrison an "inspiring, energizing and influential" in a press release.

"As former Chair of the South Carolina Democratic Party and senatorial candidate, Jaime brings an outstanding track record of success -- from galvanizing the grassroots, mobilizing millions and shattering fundraising records -- that will be critical during this pivotal moment for our Party and Country," she added.

-ABC News' John Verhovek and Beatrice Peterson

During an unscheduled stop on Capitol Hill, Vice President Mike Pence greeted National Guardsmen and telling them that he had just come from a briefing where he heard about their efforts.

He thanked the personnel for "stepping forward for your country" to make the historic transfer of power possible.

"It's been my great honor to serve as your vice president and I want to thank you for your service," Pence said.

The vice president then spoke to individual guardsmen asking them where they are from and how long they served.

About 20,000 National Guard members are expected in Washington this week to protect the city ahead of Biden's inauguration.

"Have a safe inauguration," Pence said.

-ABC News' Elizabeth Thomas and John Parkinson

Eric Lander is Biden's nominee for presidential science adviser, a position Biden announced Saturday he is elevating to a Cabinet-level position for the first time in U.S. history.

Lander served as the co-chair of the President’s Council of Advisors on Science and Technology (PCAST) during the Obama-Biden administration. He currently serves as president and the founding director of the Broad Institute of MIT and Harvard. Landon is also one of the principal leaders of the Human Genome Project.

"It's not hyperbole to suggest that Dr. Lander's work has changed the course of human history. His role in helping us map the genome, pull back the curtain on human disease, allowing scientists ever since and for generations to come to explore the molecular basis for some of the most devastating illnesses affecting our world," Biden said.

In his remarks Saturday, Lander said, "The President-Elect knows that science and technology will be crucial in meeting this moment," adding that "America's greatest asset, I think, is our unrivaled diversity. After all, scientific progress is about seeing something that no one’s ever seen before. Because they bring a different lens, different experiences, different questions, different passions. No one can top America in that regard. But we have to ensure that everyone not only has a seat at the table, but a place at the lab bench."