President-elect Joe Biden threw his weight into the Democratic battle for control of the US Senate on Tuesday, as his White House win was finally acknowledged by top Republicans and holdout foreign leaders.

Biden flew into Georgia, a southern state he won in an upset against President Donald Trump, to host a rally for two Democratic candidates in runoff races that will determine the Senate’s balance of power.

“Honk for your next United States senators Jon Ossoff and Rev. Raphael Warnock,” Biden told the crowd at the drive-in event in Atlanta, urging voters to turn out in force on January 5.

“Send me these two men, and we will control the Senate!”

One day after the Electoral College affirmed Biden’s victory, attention shifted to the looming Senate battle, and to the shape of the incoming administration as US media reported Biden will tap Pete Buttigieg, a former Indiana mayor and presidential rival, as secretary of transportation.

Buttigieg would be the first openly gay person confirmed by the Senate to a presidential cabinet post, in sync with Biden’s pledge to usher in the most diverse cabinet ever when he takes office on January 20.

And while Trump still refuses to concede, continuing to tweet allegations of mass fraud that have been rejected in dozens of lawsuits, top Senate Republican Mitch McConnell finally broke his silence with a message to the president: it’s over.

“The Electoral College has spoken. So today I want to congratulate President-elect Joe Biden,” McConnell said on the Senate floor, adding that Americans can also “take pride” that they will have their first female vice president in Kamala Harris.

Biden told reporters before flying to Georgia that he had a “good” phone conversation with McConnell, a longtime Senate colleague.

“I told him that while we disagree on a lot of things there are things we can work together on,” Biden said.

The Electoral College confirmation triggered a recognition of Biden’s win from Russian President Vladimir Putin who said he was “ready for collaboration” with the Democrat.

Brazilian President Jair Bolsonaro and Mexico’s Andres Manuel Lopez Obrador of, who had both waited until now to recognize the president-elect, also sent their congratulations.

Also read: Donald Trump ally Jair Bolsonaro acknowledges Joe Biden’s victory

Trump, in unprecedented fashion, has yet to acknowledge his defeat in the chaotic election that will see him exit the White House after a single four-year term.

Democrats, who control the House of Representatives, need to flip both Georgia Senate seats in order to seize control of the upper chamber, while Republicans must hold just one to maintain their majority.

Republicans have framed Georgia as must-win races, with the state forming the last line of defense against what they describe as radical “socialism.”

If Republicans do, McConnell remains majority leader, and his relationship with Biden will quickly become the most closely watched in Washington.