The 10-year Stacey Abrams project to flip Georgia has nearly come to fruition.

As the Democrats Jon Ossoff and the Rev. Raphael Warnock inched closer to flipping Georgia’s two Senate seats from the incumbent Republicans, credit began to flow to one person broadly acknowledged as being most responsible for Georgia’s new status as a Democratic state: Stacey Abrams.

Ms. Abrams, the former minority leader of the Georgia state House, has spent a decade building a Democratic political infrastructure in the state, first with her New Georgia Project and now with Fair Fight, the voting rights organization she founded in the wake of her losing campaign for governor in 2018.

Late Tuesday night, Ms. Abrams came close to declaring victory in a tweet that praised the thousands of “organizers, volunteers, canvassers & tireless groups” who helped rebuild the state’s Democratic Party from the rump it was when she became the state House minority leader in 2011.

While Ms. Abrams is widely expected to run for governor again in 2022, she is at the moment one of the most influential American politicians not in elected office. It was her political infrastructure and strategy of increasing turnout among the state’s Black, Latino and Asian voters that laid the groundwork for both President-elect Joseph R. Biden Jr.’s victory in November and the Democrats’ performance in the Senate races.

Ms. Abrams was not alone in Georgia, of course: Numerous other Black women have led a decades-long organizing effort to transform the state’s electorate.

“We weren’t surprised that Georgia turned blue, because we’ve been working on it for over 15 years,” Deborah Scott, the founder of Georgia Stand Up, said after Mr. Biden’s victory in the general election.

“It’s been an uphill battle,” said Felicia Davis, a longtime organizer in Clayton County. “Because here, we’re not just women, we’re Southern women. And we’re not just Southern women, we’re Southern Black women.”

Still, Ms. Abrams was the most visible face at the forefront of the turnout push. And when it came time to cut a TV ad urging Georgians to confirm the status of their absentee ballots — voters have until Friday to cure absentee ballots that contain minor errors — she appeared in the ad reminding them how to do so.

“Don’t wait,” she said. “Your vote has the power to determine the future of Georgia and our country. It’s time to make certain your voice is heard.”