Biden and Harris formally introduced newly nominated and appointed members of their administration from Wilmington, Delaware, Friday afternoon, showing off several familiar faces, be it from the Obama administration or from Capitol Hill.

For director of the White House Domestic Policy Council, a position which does not require Senate confirmation, Biden picked Susan Rice. Rice served as U.S. ambassador to the United Nations and later as national security adviser in the Obama administration.

In her remarks, Rice laid out the path of her ancestors on both sides who overcame adversity -- a paternal great grandfather who was born a slave in South Carolina and maternal grandparents who immigrated from Jamaica with no education and worked to send their children to college, leading to her mother’s role in creating the Pell Grant.

“Now at the foot of yet another bridge between crisis and opportunity, I'm honored and excited to take on this role. Joe Biden and Kamala Harris's vision for our future is expansive but achievable," Rice said, stressing her excitement to serve again and the need to develop policies that break down racial barriers that hold all Americans back.

Rep. Marcia Fudge, who has represented Ohio's 11th Congressional District for the last 12 years has been tapped for secretary of Housing and Urban Development and talked about the importance of housing in America and the need to give people hope amid  America’s ongoing crisis.

“Perhaps most importantly of all, we will help people believe once again that their government cares about them, no matter who they are. That we understand their problems, as the president-elect often recalls his father's words,” she said.

Biden's nominee for secretary of agriculture, Tom Vilsack, seemed to address some of the criticism of his previous tenure at USDA (he held the same Cabinet position he's nominated for throughout the Obama administration) by promising to deal with systemic inequities.

Vilsack also mentioned his support for Rep. Jim Clyburn's 10/20/30 plan, an effort the South Carolina congressman said aims to help counties that had a poverty level of more 20% for more than three decades. Those communities would receive at least 10% of federal funds from a specific program. When asked in 2019 if he considered the measure a form of reparations, Clyburn said the measure "absolutely" is.

Biden's pick for secretary of veterans affairs, Dennis McDonough, former President Barack Obama's White House chief of staff, pledged to make the department more inclusive to all veterans, particularly women, veterans of color and members of the LGBTQ community.

Biden's appointed Katherine Tai to U.S. trade representative, who began by recalling her parents' immigrant story of her father, a researcher at Walter Reed, and her mother, who still works at the National Institutes of Health developing treatments for opioid addictions. She also stressed the role trade can play to create opportunities and lift people out of poverty and the need to rebuild relationships around the globe.

-ABC News' Molly Nagle, John Verhovek and Beatrice Peterson

Rep. Bill Pascrell, D-N.J., has called on House Speaker Nancy Pelosi to refuse to seat those Republicans who signed on to a brief supporting the Texas lawsuit seeking to throw out millions of votes when the next Congress is sworn in next year.

"Stated simply, men and women who would act to tear the United States government apart cannot serve as Members of the Congress," he said. "These lawsuits seeking to obliterate public confidence in our democratic system by invalidating the clear results of the 2020 presidential election undoubtedly attack the text and spirit of the Constitution, which each Members swears to defend."

“The House still retains the right to decide who is seated,” Pelosi said in 2018, amid concerns of fraud impacting the election in North Carolina's Ninth Congressional District. “Any member-elect can object to the seating or the swearing in of another member-elect, and we’ll see how that goes.”

-ABC News' Benjamin Siegel

Biden is introducing more nominees and picks for the incoming administration from Wilmington, Delaware, and while the resurgence of Obama-era officials has some Democrats worried the president-elect is relying so heavily on his longtime allies, Biden argued the choice behind each of his picks Friday.

"Vice President-Elect Harris and I knew we’d have our work cut out for us when we got elected, but we also knew we could build a team that would meet this unique and challenging moment in American history. Some are familiar faces. Some are new in their roles," Biden said. "Above all, they know how government should and can work for all Americans."

For secretary of agriculture, Biden’s nominating Tom Vilsack, who served in the same post throughout the Obama administration. Vilsack previously served two-terms as governor of Iowa.

For secretary of Housing and Urban Development, Biden chose Rep. Marcia Fudge, who has represented Ohio's 11th Congressional District for the last 12 years. If confirmed, she will be the first woman to lead the department in more than four decades.

For secretary of veterans affairs, Biden is nominating former President Barack Obama’s former chief of staff, Denis McDonough. McDonough also served as deputy national security adviser and chief of staff of the National Security Council during the Obama administration.

Biden picked Katherine Tai for U.S. trade representative. Tai currently serves as the chief lawyer on trade for the Ways and Means Committee in the House of Representatives and previously was chief counsel for China trade enforcement in the office of the U.S. trade representative.

For director of the White House Domestic Policy Council, Biden has appointed Susan Rice. Rice served as U.S. ambassador to the United Nations and later as national security adviser in the Obama administration.

Before introducing more Cabinet nominees and administration picks to the public on Friday, Biden opened with a statement on Pfizer and BioNTech’s coronavirus vaccine, which the Food and Drug Administration is expected to approve for emergency use at any time.

"I want to make it clear to the public: You should have confidence in this. There is no political influence,” Biden said.

Biden’s remarks come as sources familiar with the matter tell ABC News White House chief of staff Mark Meadows in a phone call on Friday suggested to FDA Commissioner Dr. Stephen Hahn that his job could be on the line if his agency doesn't authorize the emergency use for the vaccine by the end of the day.

-ABC News’ Katherine Faulders and John Santucci

Trump and Biden hold dueling events on the pandemic response Tuesday with the president hosting a "vaccine summit" at the White House, just days before a Food and Drug Administration advisory committee holds a hearing on whether to authorize emergency use of a COVID-19 vaccine, while the president-elect is slated to formally roll out his health care picks who will take over handling the COVID-19 pandemic in 43 days.

At his event, Trump is slated to sign an executive order touting his mantra of "America First" that would prioritize Americans’ access to COVID-19 vaccines before the United States helps other countries. But the chief science adviser to "Operation Warp Speed," the U.S. government's initiative to expedite vaccine development which Trump is also expected to tout, said Tuesday morning he doesn't know about the vaccine-related executive order Trump is expected to sign.

"Frankly, I don't know and, frankly, I'm staying out of this. I can't comment," Dr. Moncef Slaoui told ABC News Chief Anchor George Stephanopoulos in an interview Tuesday on "Good Morning America,” when asked to explain the executive order.

The event comes as a senior administration official familiar with the matter confirmed reporting to ABC News that the Trump Administration passed when Pfizer offered in later summer to sell the U.S. more COVID-19 vaccine doses -- an approach which the White House has denied and Slaoui defended Tuesday. Representatives of Pfizer and Moderna -- the two drug companies seeking emergency-use authorization -- are not expected to attend the White House summit, nor is anyone from the Biden transition team.

Biden, meanwhile, is slated to introduce the health care team he will entrust with handling the pandemic California Attorney General Xavier Becerra as Health and Human Services secretary, the first Latino to hold the post if confirmed. Director of the National Institute of Allergy and Infectious Diseases Dr. Anthony Fauci, who is taking on the elevated role of chief medical adviser to Biden in the incoming administration, is expected to dial into Biden’s meeting, though not the one at the White House.

Biden and Vice President-elect Kamala Harris are also meeting Tuesday with several civil rights leaders including NAACP representatives to discuss policy issues around racial equity as well as diversity and representation on the incoming Cabinet. It comes after news leaked that Biden is expected to name retired four-star Army Gen. Lloyd Austin as his defense secretary, who would be the first African American in the post if confirmed, this week.

Tuesday is also the congressionally mandated "safe harbor" deadline -- the date, under federal law, by which the "final determination of any controversy or contest concerning the appointment" of electors "shall be conclusive” -- making it extremely difficult to dispute election results in the courts, where pro-Trump efforts have seen at least 39 defeats to date.