The nod was among dozens of endorsements of Democratic candidates across the country released by Obama on Twitter.
Warnock, who is pastor of the Atlanta church where the Rev. Martin Luther King Jr. preached, is one of 20 candidates challenging Republican Sen. Kelly Loeffler for the seat she was appointed to by Georgia’s governor 9 months ago.
Even with broad support from party leaders, Warnock has struggled somewhat to connect with voters. He has consistently ranked just behind Loeffler and Republican Rep. Doug Collins in public polling, though he has been on the rise in recent weeks.
That’s raised fears among Democrats that they could get locked out of a Jan. 5 runoff, required by state law if no candidate tops 50% on Nov. 3. It's also led to a pressure campaign to push other Democrats, including Matt Lieberman, an educator and son of former Sen. Joe Lieberman, out of the race in order to consolidate support behind Warnock.
“If we want a real leader, we need Matt Lieberman to understand that he is not called for this moment and to step back and to let support consolidate around Raphael Warnock so that he can lead,” Stacey Abrams, another high-profile Democrat who has endorsed Warnock, said Thursday.
Lieberman has so-far resisted calls to bow out. “We Democrats must be about giving the people the right to choose who will lead them, and not limiting that choice before they even have a chance to vote," he said on Twitter.
Warnock's campaign declined to comment on calls for Lieberman to drop out.
Democrats aren't the only ones squabbling among themselves. Loeffler and Collins, both Trump loyalists, have been locked in a bruising battle as both seek support from the right flank of the Republican party.
The race is one of two U.S. Senate contests in Georgia that will be on the ballot this fall. In the other race, Republican Sen. David Perdue faces Democrat Jon Ossoff, who was also endorsed by Obama on Friday.