In his first official public endorsement since leaving office, former President Donald Trump backed Sarah Huckabee Sanders' campaign for governor of Arkansas on Monday, hours after the former White House press secretary officially announced her bid.

Trump released the statement backing Sanders via his new political action committee, Save America, calling his former aide "a warrior who will always fight for the people of Arkansas and do what is right, not what is politically correct."

"Sarah will be a GREAT Governor, and she has my Complete and Total Endorsement!" the statement reads.

Trump had previously publicly encouraged Sanders to run for governor.

-ABC News' Will Steakin

Senate Minority Leader Mitch McConnell said Monday night that he will allow the Senate power-sharing agreement brokered with Majority Leader Chuck Schumer to go forward, solidifying how the evenly tied Senate will function for the next two years.

Specific details of the agreement are not yet clear, but McConnell cites statements from two Democratic members -- Sen. Joe Manchin, D-W.Va. and Sen. Kyrsten Sinema, D-Ariz -- who have said they will not vote to overturn the Senate filibuster rule as the reason he is allowing the agreement to move forward.

Progress on reaching a power-sharing agreement stalled when McConnell announced he wanted assurances from Schumer that he would not overturn the filibuster rule. If Schumer had wanted to do this it would have required the unanimous support of his caucus.

"The legislative filibuster was a key part of the foundation beneath the Senate's last 50-50 power-sharing agreement in 2001. With these assurances, I look forward to moving ahead with a power-sharing agreement modeled on that precedent," McConnell wrote in a statement.

Justin Goodman, a Schumer spokesperson, released a statement in response to the move.

"We're glad Senator McConnell threw in the towel and gave up on his ridiculous demand. We look forward to organizing the Senate under Democratic control and start getting big, bold things done for the American people," Goodman said in the statement.

--ABC News' Allison Pecorin

Former President Donald Trump Monday opened an "Office of the Former President," according to a statement from the office.

"The Office will be responsible for managing President Trump's correspondence, public statements, appearances, and official activities to advance the interests of the United States and to carry on the agenda of the Trump Administration through advocacy, organizing, and public activism," the statement read.

The announcement comes the same day that House Democrats delivered an article of impeachment to the Senate, setting in motion the second impeachment trial against Trump in the chamber.

-ABC News' Ben Gittleson

Biden continued with his calls to world leaders Monday, this time speaking with German Chancellor Angela Merkel and agreeing to revitalize the two countries alliance.

They agreed that cooperation was important to meet the challenges of the COVID-19 pandemic and climate change. They also said the U.S. and Germany would work together on foreign policy issues regarding Afghanistan, Iran, China, Russia, Ukraine and the Western Balkans.

Biden started making calls to foreign leaders on Friday, first reaching out to the leaders of Canada, Mexico and the U.K. on Friday and the French president on Sunday. COVID-19 was also a main point of conversation on those calls.

-ABC News' Justin Gomez