Biden is expected to name former 2020 rival and South Bend Mayor, Pete Buttigieg to head the Department of Transportation, sources familiar with the transition tell ABC News.

If confirmed Buttigieg, 38 would be the youngest pick yet for Biden's cabinet, and the first openly gay cabinet secretary approved by the U.S. Senate to serve in U.S. history.

Buttigieg endorsed Biden in March shortly after ending his own presidential campaign and campaigned on behalf of Biden during the general election. Biden, spoke highly of Buttigieg following his endorsement, saying he reminded Biden on his late son, Beau.

-ABC News' Molly Nagle, Justin Gomez and Katherine Faulders

Speaking on the tarmac in Delaware ahead of his trip to Georgia to campaign for Democratic candidates in the Senate runoffs there, Biden confirmed he spoke with Senate Majority leader Mitch McConnell -- who acknowledged Biden's victory for the first time on Tuesday -- saying they had a "good conversation" and expressed his hope that they could work together in the future.

"I had a good conversation with Mitch McConnell today. We talked -- so I called to thank him for the congratulations, told him although we disagree on a lot of things, there’s things we can work together on. We’ve always been straight with one another, and we agreed we’d get together sooner than later. And I’m looking forward to working with him," Biden said.

Biden went on to tell reporters that he has been speaking with other members of Congress, saying about “a dozen” have been calling him. Biden promised to tell the press who he has spoken to.

“I just want you to know I spoke with him, and I’ve been calling other members. I spoke with some other members as well," Biden said. "As I tick them off I’ll tell you who’s calling."

Asked when he would receive the coronavirus vaccine, which Biden has said he'll do publicly, he confirmed that it would be soon but stressed that he wanted to do it “by the numbers."

“Dr. Fauci recommends I get the vaccine sooner than later.I want to just make sure we do it by the numbers, and we do it -- but when I do it, you’ll have notice and we’ll do it publicly,” Biden said.

-ABC News' Sarah Kolinovsky, John Verhovek and Molly Nagle

The top State Department official for conflict operations is resigning, according to internal emails obtained by ABC News.

Denise Natali, the assistant secretary of state for conflict and stabilization operations, will depart the agency Friday, telling her staff in an email Tuesday, "It has been an honor to work with you for the past two years. I am extremely grateful for your commitment, hard work, and support."

"You are making significant contributions to U.S. foreign policy, particularly in carrying out our mission to anticipate, prevent, and respond to conflict that undermines U.S. national interests. I am very proud of what you have accomplished and am confident that you will continue to do great work in the years ahead," she added.

Natali is the first senior department official appointed by Trump and confirmed by the Senate to resign after Biden defeated their boss in the 2020 presidential election. Jim Jeffrey, a veteran diplomat who was Secretary of State Mike Pompeo's special envoy for Syria, departed in November.

A State Department spokesperson confirmed to ABC News her last day is Friday.

Natali joined the Trump administration in October 2018 from the National Defense University. During her tenure, she led U.S. delegations from Colombia to Niger to Bulgaria on countering violent extremism, coordinating responses with U.S. allies, reintegrating terrorist fighters and stabilizing conflict-ridden countries.

Her note made no mention of the 2020 election. But the department has been working with Biden's transition team, providing briefings and office space, even as Pompeo has yet to fully acknowledge Biden's victory. The agency "will do everything that's required by law" to facilitate the transition, he said on Nov. 24, two weeks after quipping there would be a "smooth transition to a second Trump administration."

CNN reported Tuesday that includes a meeting this Thursday between him and Biden's choice to succeed him, Anthony Blinken, which would be their first. A State Department spokesperson told ABC News, "There is no meeting planned or confirmed," after Pompeo told the Washington Examiner Monday they'll meet "at the right time."

-ABC News' Conor Finnegan

The Presidential Inaugural Committee, in a new statement Tuesday, has confirmed that Biden and Vice President-elect Kamala Harris will take their oaths of office at the U.S. Capitol in an inauguration that will include "vigorous health and safety protocols" and a "reimagined" parade.

"Our goal is to create an inauguration that keeps people safe, honors the grand traditions of the Presidency, and showcases the Biden-Harris Administration’s renewed American vision for an inclusive, equitable, and unified citizenry,” said committee CEO Tony Allen in the statement.

Organizers are encouraging people to stay home and not travel to Washington, D.C., for the inauguration as Biden tries to model good public health behavior amid the worsening coronavirus pandemic. The limited festivities will be produced by Stephanie Cutter and Ricky Kirshner, who put together the Democratic National Convention program over the summer. Much like the DNC, the inauguration will have several virtual elements.

Capitol officials have already confirmed that they plan to implement coronavirus testing for everyone expected to come into close contact with Biden and Harris on Jan. 20.

The committee's statement also announced that Dr. David Kessler, a former Food and Drug Administration commissioner who is advising Biden's transition, will be the inaugural committee's chief medical adviser.

-ABC News' Benjamin Siegel