Biden is expected to name Rep. Deb Haaland his nominee for interior secretary, according to sources familiar with his plans -- a historic move that would make her the first Native American to lead the department managing public lands and relations with the country's Indigenous people.

A member of the Laguna Pueblo tribe, Haaland, if confirmed, would lead an agency that manages roughly 450 million acres of public land in the United States -- including national parks and wildlife habitats -- along with education and health programs for the 574 federally recognized tribes. She marks another historic pick in Biden's Cabinet he has touted as "full of firsts."

She would also play a major role in implementing Biden's climate agenda -- and carrying out his pledge to limit new oil and gas drilling on public lands.

Haaland is the third House Democrat to join the Biden administration, which will leave the party's already thin House majority even slimmer in the opening months of the Biden administration.

Democrats currently hold 222 seats in the House, with two races still outstanding, and would hold just 219 seats when Haaland, Reps. Cedric Richmond and Marcia Fudge leave Congress.

Still, House Democratic leaders publicly signaled this week that they had no objections to Haaland's selection, with Speaker Nancy Pelosi supporting the pick in a statement on Wednesday.

Progressives and indigenous groups applauded the news of Haaland's selection Thursday.

"With the historic appointment of Deb Haaland as Interior Secretary, Joe Biden chose the most qualified person and put a true movement progressive in his Cabinet. We're thrilled that Deb will fight alongside Janet Yellen, Xavier Becerra, and others for the ambitious policy priorities that Biden campaigned on," Stephanie Taylor of the Progressive Change Campaign Committee said in a statement.

Hilary C. Tompkins, who served under President Barack Obama as the first Native American to hold the position of solicitor in the department, called the decision "historic."

"Rep. Haaland will bring her wisdom, lived experiences as a Native woman, and great leadership to Interior for the betterment of our public lands and waters, the trust relationship, and wildlife protection," Tompkins said.

Rep. Raul Grijalva, D-Ariz., the chairman of the House Natural Resources Committee, told ABC News that Haaland will bring an "outside perspective" to the Interior Department, and dismissed early GOP criticism based on her support for the Green New Deal and other progressive proposals.

"Some senators can saber-rattle, but she’s going to get confirmed," he said. "It's difficult to stand in front of history and try to stop it."

-ABC News' Benjamin Siegel and Molly Nagle

Anthony Blinken, Biden’s nominee for secretary of state, is at the State Department’s main headquarters in Washington on Thursday, transition spokesperson Ned Price told ABC News.

Blinken and his team are “taking part in meetings and briefings” and “following strict COVID protocols,” Price said.

“We expect he will continue to attend occasional in-person meetings at the department in the coming weeks, as has been standard practice for previous nominees for the role,” he added.

While there were reports that Blinken and Pompeo would meet at State -- marking the first Cabinet-level meeting between the Trump administration and the Biden transition -- that meeting is not taking place Thursday with Pompeo still at home in quarantine after COVID-19 exposure.

Neither Biden's transition team nor the State Department has said whether that meeting will now happen virtually. It's still unclear when or where the top U.S. diplomat was exposed to COVID-19 or by whom, a detail the State Department said it won't confirm for privacy reasons.

-ABC News’ Conor Finnegan and Molly Nagle

Vice President Mike Pence touched down in Columbus, Georgia, Thursday afternoon to stump for sitting Sens. Kelly Loeffler and David Perdue on the fourth day of early voting in that state for runoff races which will determine the balance of power in the U.S. Senate.

"It all comes down to Georgia," he told the crowd.

"I bring greetings from the 45th president of the United States, President Donald Trump," Pence said at the top of the first of two rallies Thursday to cheers. "We're gonna keep fighting for every legal vote in America. And we're gonna to keep fighting to hold the line in the United States Senate."

In referring to Biden's visit to Atlanta earlier in the week, when he campaigned for Democratic challengers Jon Ossoff and Rev. Raphael Warnock, Pence avoided directly recognizing Biden as the president-elect but acknowledged the Georgia runoffs as the GOP's "last line of defense."

"He said that we didn't need to go back to Washington. Because he said, "We don't need two senators that are just going to get in the way." Well Georgia, that's exactly what we need in the United States Senate. We need David Purdue and Kelly Loeffler to get in the way."

In a reversal from GOP messaging in the presidential election, Pence pushed absentee voting as an option, directing Georgians to a website to request their ballots "today."

"I want you to be confident about your vote, right David?" Pence said, to the senator who, along with Loeffler, joined a Texas Supreme Court lawsuit seeking to nullify ballots in their state. "Our great GOP state chairman and the senators will tell you, you request a ballot. We're on it this time. We're watching."

Trump has attacked Republican officials in the state over absentee ballots for weeks despite signature matching done twice for those ballots and three counts of the presidential vote there. Biden is the first Democrat to win the state of Georgia since 1992, and senators speaking ahead of Pence urged voters to show the country Georgia is a red state.

How's this for party unity? Rep. Alexandria Ocasio-Cortez and Sen. Jon Tester agree ... that current Democratic leaders in Congress aren't the right faces for their segments of the Democratic Party.

How's this for bipartisanship? If Americans get another round of stimulus checks, they'll have the teamwork of ... Sen. Bernie Sanders and Sen. Josh Hawley in part to thank.

Those are just tastes of the tangled intra- and interparty dynamics that await Biden and Vice President-elect Kamala Harris.

Washington isn't really working. When it does work it does so in sporadic and sometimes chaotic fashion, as with year-end deals to keep the government open and potentially resume COVID-19 relief funds.

For a party about to assume the presidency, keeping control of the House and still in the hunt for the Senate, Democrats are still all over the map -- even arguing over what the map should look like.

They're about to lose the thing that unites them most effectively -- President Trump -- at a time of continuing national crisis, and with a Republican Party that will be searching for its new, post-Trump identity.

Much of this will be left to Biden to sort out. There's a difference between claiming a mandate and finding votes -- assuming they want to be found.

-ABC News' Political Director Rick Klein