A surge in turnout from Georgia’s Black voters has powered the fortunes of the Rev. Raphael Warnock and Jon Ossoff, putting the Democrats within reach of flipping two Senate seats and winning control of the chamber.
Predominantly Black counties across rural Georgia have had turnout for Mr. Warnock and Mr. Ossoff that nearly matched the Nov. 3 general election and margins that exceeded what President-elect Joseph R. Biden Jr. received when he defeated President Trump in the state.
In Calhoun County, which is 61 percent Black and where most ballots had been counted late Tuesday, Mr. Warnock was ahead by 19 percentage points out of 2,031 votes cast and Mr. Ossoff had an edge of 18 points, compared with Mr. Biden’s 15 percent margin out of 2,198 votes in November.
In Clay, Macon, Randolph and Washington Counties, all small, rural, predominantly Black counties, Mr. Ossoff and Mr. Warnock won larger margins than Mr. Biden did with turnout that nearly reached the November figures — an extraordinary feat given the nature of the runoffs.
Some of Georgia’s largest counties in metropolitan Atlanta, which is home to the state’s largest concentration of Black voters, have yet to report a majority of their votes, though they are expected to soon.
Data from TargetSmart, a Democratic political data firm, found that nearly 50,000 Black Georgians had cast early ballots in the Senate runoffs after not voting in the Nov. 3 general election.
Scores of grass-roots organizations worked to turn out Black voters in the lead-up to the runoffs, and on a campaign swing last weekend, Vice President-elect Kamala Harris targeted Black neighborhoods where early-voting turnout had been soft.
“The Black vote delivered the U.S. Senate for Democrats,” said Tom Bonier, the chief executive of TargetSmart.