Collins conceded to Loeffler before the Associated Press called a runoff between the two candidates late Tuesday, saying she had his “support and endorsement.” Loeffler had spent much of her campaign trying to distinguish herself from Collins via social media attacks and other messaging, branding herself the stronger conservative.

Trailing behind all three in public polling was another Democrat, Matt Lieberman, the son of former Sen. Joseph Lieberman, who stayed in the race despite concerns among Democrats that he and Warnock would split votes and potentially lock the party out of the Senate runoff if Loeffler and Collins both finished ahead of them.

But Lieberman’s standing in the polls fell dramatically when former President Barack Obama and other Democrats endorsed Warnock, senior pastor at Atlanta’s Ebenezer Baptist Church, which was once the pastoral home of Martin Luther King Jr. Stacey Abrams was another big-name Democrat to back Warnock.

Early voting in Georgia saw a near-110 percent increase since 2016, despite long lines during the first week with waits as long as 11 hours. The participation of Black voters had been on track to outpace turnout for 2008, when then-candidate Obama was swept into the presidency.

The special election is taking place because former Sen. Johnny Isakson, a Republican, resigned from his seat a year ago due to health reasons. Gov. Brian Kemp appointed Loeffler to the seat, but Collins decided to run against her.

Loeffler, the appointed GOP incumbent, delivered a speech to supporters shortly after the runoff was called.

“In January, I have one of the most radical opponents on the Democratic ticket in the whole country: Raphael Warnock,” she said, to boos from attendees.

Loeffler emphasized her strong alignment with President Donald Trump’s agenda during her monthslong tenure in the Senate, which started in January.

Warnock addressed his supporters as well, shortly before the runoff was called. He said both Loeffler and Collins would aim to repeal the Affordable Care Act, the cornerstone legislative achievement of the Obama administration.

“People who lack vision traffic in division. They cannot lead us so they will try to divide us. I submit that we’re all we got,” he said. “So while they try to tear me down, I’m going to be busy trying to lift the families of Georgia up.”

Twitter, though, left alone a similar Trump campaign tweet declaring victory in Florida because, the company said, it included a nod to one of Twitter’s seven approved race callers. In a seeming acknowledgment of Twitter’s rules there, the campaign appended to its Florida victory tweet a note reading, “Source:@DecisionDeskHQ.”

A Trump campaign representative did not immediately respond to a request for comment.

The country’s biggest social media companies have in recent days said that so-called premature declarations of victory were one of their primary concerns headed into this fraught Election Day, especially on a night expected to be full of close contests across the country. A final verdict on who wins the presidency could take days or weeks depending on how the vote-counting, recounts and assorted court battles play out.

POLITICO, at the moment, has declared South Carolina for Trump but is still listing Florida as “too close to call.”

SAN FRANCISCO — Gov. Gavin Newsom raised the possibility Tuesday that California could permanently move to its pandemic-driven approach of mailing all voters a ballot after the state saw record early turnout for the November election.

Before Tuesday’s polls opened, more than 12 million California voters had submitted ballots, over half of those registered in the state. The state moved to an all-mail system in an attempt to deter crowds from polling places during Covid-19.

“We’ll discuss that with the Legislature, but I think making voting easier, providing more choice and more opportunity is fabulous,” Newsom said in an Election Day get-out-the-vote stop at Manny’s, a Mission District hot spot. With so many California voters already having cast ballots, Newsom spent his morning texting hundreds of individual voters in the critical swing state of Pennsylvania.

The Democratic governor said Tuesday that California’s system has exceeded expectations — and appears a proven success if turnout is the measure. Experts believe the state is well on its way toward shattering its 2016 record of 14.6 million ballots cast.

“This trend has predated Covid in California — a significant increase, election after election, in people voting by mail and absentee … Covid has accelerated that trend,’’ he told reporters. “And I think the expectations will be all across this country that people will demand more choice so they can exercise their voice.”

“That’s a good thing — as long as we can track, as long as everybody feels confident in that system and process,” he added.

Newsom in May signed an executive order mandating that all registered voters in California would receive a ballot for the November election — a move he said was necessary because no state resident “should have to risk their health in order to exercise their right to vote.”

The Legislature followed suit with a bill enacting the same approach, intended to bolster the mail election against legal challenges. The bill passage was prescient; a Sutter County judge on Monday ruled in favor of two Republican assemblymembers who alleged that Newsom have overstepped his executive authority by ordering an election change.

California was already on its way toward a system that mails all voters a ballot. A 2016 law called the Voter’s Choice Act enabled select counties to do so, and five counties took that approach in 2018. Ten additional counties signed on for this year. But when the pandemic struck, the Voter’s Choice Act became an immediate model for the entire state.

While all registered, active voters receive a ballot, they do not have to rely on mailing them in. They can also turn in their ballots at drop boxes located throughout their counties — anywhere from grocery stores to government offices.

They also can take their ballot to a vote center and participate in person; the centers have more services, allowing residents to register to vote, update their address or obtain a ballot if they never received one. This year, professional sports arenas opened their doors to serve as massive vote centers to accommodate larger numbers.

Democrats dominated the first three weeks of early voting, encouraged by party leaders to participate as early as possible to avoid any late election challenges such as U.S. Postal Service delays or long lines at polling places. But Republican turnout numbers increased as California opened vote centers in the past two weeks.

Voting by mail became politicized this year, with President Donald Trump and Republicans taking aim at California in particular. They alleged that the state’s mail ballot system was vulnerable to fraud, which drove many Republicans to vote in person rather than send in their absentee ballots, a reversal of past behavior.

Republicans also had cast aspersions on the mail balloting system after the 2018 midterm elections that saw Democrats reduce the GOP’s House membership to seven out of 53 seats. Republicans pointed to a “ballot harvesting” system that involved Democratic volunteers picking up ballots from voters and delivering them to elections offices. The GOP countered this fall with unofficial ballot boxes posted in battleground congressional districts that triggered a legal battle with Democratic state officials.

Newsom’s suggestion Tuesday that the system could be a permanent feature in California elections was met with enthusiastic praise by a crowd of other elected officials on hand at the Election Day event.

“Definitely … it’s one of the reasons we had such a high voter turnout here,” said San Francisco Mayor London Breed. “In San Francisco, we made it so easy for people,’’ a contrast to “what I’ve seen in other parts of the country, where voters are disenfranchised, that breaks my heart.”

Kevin Yamamura contributed to this report.