Trump-Biden transition: Attorney Sidney Powell back at White House Sunday

President-elect Joe Biden is expected to name Gina McCarthy, who served as administrator of the Environmental Protection Agency under President Barack Obama, his top domestic climate policy aide, according to a source familiar with the decision. 

McCarthy, who currently serves as the president of the National Resources Defense Council, is expected to coordinate domestic efforts to slow climate change across the administration from the White House. 

It's the second climate-focused White House position created by Biden, following his decision to enlist former Secretary of State John Kerry to serve as a climate envoy, coordinating policy with other countries.  

In addition to her work in the Obama administration as EPA administrator from 2013-2017, McCarthy served as commissioner of the Connecticut Department of Environmental Protection, and in several similar posts in Massachusetts, where she advised several governors on environmental issues.

-ABC News' Benjamin Siegel and Molly Nagle

Some of President Trump's Republican allies are still committed to challenging the 2020 election results on the floor of the House of Representatives next month -- even as Senate Republicans have begun acknowledging Biden's status as the president-elect.  

"I have a choice -- I can either fight, or I can join the surrender caucus," Rep. Mo Brooks, R-Alabama, one of the leaders of the effort to challenge the certification of the Electoral College, told ABC News. 

Brooks said Monday's Electoral College vote hasn't changed his plans, but he has yet to find a GOP senator to back him. Without one, he can't force Congress to debate and vote on whether to accept a given state's slate of electors. 

"This is purely performative," Michael Waldman, president of the Brennan Center, told ABC News of the long-shot challenge, comparing it to the Texas Supreme Court lawsuit that unsuccessfully sought to overturn the results in several key states. 

Forcing senators on the record "purely creates political pain right now for Republicans," he said. 

Republican leaders in the Senate, wary of such a vote, have also privately discouraged members from signing on. 

Senate Majority Leader Mitch McConnell, soon after recognizing Biden as the president-elect, warned Republicans on a conference call that a Jan. 6 fight over electors would be a "terrible vote" and divisive for the party, sources familiar with the comments told ABC News. 

-ABC News' Benjamin Siegel and Trish Turner

Biden is expected to name former Michigan Gov. Jennifer Granholm to head the Department of Energy, sources familiar with the decision confirmed to ABC News on Tuesday.

That would make Granholm, 61, the ninth woman Biden has nominated so far to serve in his cabinet. If confirmed by the Senate, the former two-term governor would be just the second woman to lead the Energy Department.

A source familiar with the transition team's thinking pointed to Granholm’s work with Biden in Michigan during the 2009 recovery that rescued the U.S. auto industry and led to investments in green energy jobs in the state -- something Biden’s ambitious infrastructure plan would also seek to invest in.

-ABC News' John Verhovek, Molly Nagle and Benjamin Siegel

Biden has announced his intention to nominate Pete Buttigieg to serve as his secretary of transportation, as earlier reported by ABC News. 

If confirmed, Buttigieg, 38, would be the youngest pick yet for Biden’s cabinet and the first non-acting LGBTQ department head in history.

In a statement, Biden called Buttigieg a "patriot and a problem-solver," and said he was nominating the former mayor of South Bend, Indiana, "because this position stands at the nexus of so many of the interlocking challenges and opportunities ahead of us" -- jobs, infrastructure, equity and climate.

Buttigieg said he was honored to be asked to serve in the position.

"This is a moment of tremendous opportunity -- to create jobs, meet the climate challenge, and enhance equity for all," he tweeted following the announcement.