Everton Blair Jr., a former chair of the Gwinnett County School Board in Georgia, won a special election runoff on Tuesday to serve the remainder of Representative David Scott’s term after his death in April, according to The Associated Press.

Mr. Blair and Aisha Wahab, a California state senator who won a special election last week to fill former Representative Eric Swalwell’s seat, are set to cut Republicans’ majority in the House down to just four members. Currently, Republicans have a thin edge of 218 seats to 212 for Democrats.

Mr. Blair defeated Marcye Scott, the congressman’s daughter, in a runoff that pitted a local education leader against a prominent political family. Mr. Scott, a Democrat who represented the deep-blue district in Atlanta’s eastern suburbs for 12 terms, died on April 22 at age 80.

Mr. Blair will head to Washington only for the remaining months of Mr. Scott’s term, which ends in January. He is not running in the November general election, which will determine who serves the district’s next full term.

The Democratic nominee in that race is State Representative Jasmine Clark, who was running against Mr. Scott in the primary when he died and is now heavily favored to win the seat in the fall.

Mr. Blair earned just under 12 percent of the vote in the Democratic primary on May 19 that Ms. Clark won. Ms. Clark chose not to run in the special election to fill the seat.

Ms. Clark will face Jonathan Chavez, the Republican nominee, in November. Mr. Chavez ran against Mr. Scott in 2024 and lost by more than 40 percentage points.