ATLANTA — Democrats moved a major step closer to capturing control of the Senate on Wednesday morning as Georgia voters elected the Rev. Raphael Warnock, the pastor at the storied Ebenezer Baptist Church, in a hard-fought runoff contest that became roiled by President Trump’s false claims of voter fraud in the state.
Mr. Warnock’s victory over the Republican incumbent, Kelly Loeffler, was called by The Associated Press early Wednesday. It represented a landmark breakthrough for African-Americans in politics as well as for Georgia: He became the first Black Democrat elected to the Senate from the South.
For Democrats to take the Senate, which is crucial to enacting President-elect Joseph R. Biden Jr.’s first-term agenda, they also need to win Georgia’s other Senate runoff held on Tuesday. With an estimated 98 percent of votes counted in that race as of 4 a.m. Wednesday, the Republican candidate, David Perdue, trailed his Democratic rival, Jon Ossoff, by 12,806 votes.
Turnout in rural, overwhelmingly white counties where Republicans needed a strong showing was lagging without Mr. Trump on the ballot, and many of Georgia’s heavily Black localities saw turnout levels that neared those of the presidential race in November.
While Mr. Warnock’s win was a major gain for his party — he is the first Democrat to be elected to the Senate from Georgia since 2000 — both political parties remained on edge over the unresolved Ossoff-Perdue race and its implications for the next two years in American politics. Whichever party wins that race will control the Senate, with Republicans counting on Mr. Perdue to prevail and give them the ability to constrain Mr. Biden’s policy ambitions.
Ms. Loeffler had rebranded herself as a hard-line Trump loyalist to fend off a challenge from the right in the first round of voting. In recent weeks, she continued to embrace the president, even using an election-eve rally with Mr. Trump in northwest Georgia to proudly declare that she would oppose certifying his loss to Mr. Biden when Congress meets on Wednesday.
Mr. Warnock and Mr. Ossoff ran as a virtual package deal, as did the two Republicans, often appearing at events together and crafting similar messages about the stark consequences for the nation if the other side won. Republicans used much of the runoff to focus on Mr. Warnock’s sermons, a line of attack that appeared to mobilize African-American voters, especially in more conservative rural Georgia where the church is a pillar of many communities.
Mr. Trump’s refusal to acknowledge his defeat also robbed Ms. Loeffler of what might have been her best argument in what is still a slightly right-leaning state — that she would be a check on the liberal excesses in a government fully controlled by Democrats.
Even before polls closed on Tuesday, senior Republican campaign officials were pinning the blame on the president, noting that their polling testified to the power of the “check-and-balance” argument the party was unable to make because of Mr. Trump’s denial.