Georgia's GOP gubernatorial candidate Brian Kemp resigns as secretary of state

• Republican Brian Kemp resigned Thursday as Georgia secretary of state.
• Kemp, who is running for the state governor's office against Democrat Stacey Abrams, has faced accusations of using his job as the state's top election official to influence his gubernatorial bid.
• While Kemp has declared victory, Abrams has not conceded and NBC News still considers the contest too close to call.

Gubernatorial candidate Brian Kemp adjusts his tie before speaking to volunteers and staff at his campaign office as they hold a phone banking event in Atlanta, Georgia, U.S.

Leah Millis | Reuters

Georgia's Republican secretary of state, Brian Kemp, resigned Thursday as his gubernatorial race with Democrat Stacey Abrams remains too close to call.

In a statement, the Georgia secretary of state's office said Kemp submitted his resignation effective at 11:59 a.m. Thursday. The Republican was the state's top election official as he ran to become its governor, and stepping down means he would not certify the final vote count — despite his ability to influence the election previously.

He declared victory Wednesday in his contest with Abrams, which was marked by concerns about Kemp using his current office to suppress votes. Abrams, a former state House minority leader who aims to become the first black woman to serve as a U.S. governor, has not conceded yet.

The Republican candidate had won roughly 50.3 percent of the votes counted in the race as of Thursday morning, according to NBC News tallies. The figure is important because, if Kemp secures less than a majority of votes, the contest will go to a runoff.

On Thursday, the Georgia Democratic Party called Kemp's "self-coronation" a "legally meaningless political stunt." The party noted that the state had not officially certified votes in the race.

Georgia Democrats tweet

A lawsuit filed by Georgia voters on Tuesday in a federal court in Atlanta accused Kemp of using "the official powers of his office to interfere in the election to benefit himself and his political party and disadvantage his opponents." In a statement to NBC News on Tuesday night, Kemp spokeswoman Candice Broce called the litigation a "twelfth-hour stunt."

Democrats and voting rights groups argued Kemp should have stepped down before the election. Former President Jimmy Carter — who served as Georgia's governor and lives in the state now — called on Kemp to resign.

"In order to foster voter confidence in the upcoming election, which will be especially important if the race ends up very close, I urge you to step aside and hand over to a neutral authority the responsibility of overseeing the governor's election," Carter wrote in October, according to a copy of the letter obtained by The Associated Press.

Voter suppression concerns included roughly 50,000 voter registrations — largely affecting black voters — being put on hold. Reports of long lines and voting machine issues also surfaced.

— CNBC's Tucker Higgins contributed to this report.