SAVANNAH, Ga. (AP) — Democratic Sen. Raphael Warnock’s campaign said Wednesday that he raised a hefty $9.8 million in the last quarter of 2021, nearly double the fundraising haul reported by the leading Republican contender for his seat, former football star Herschel Walker.

Walker’s campaign said in a statement Wednesday that he raised $5.4 million in the three-month period ending Dec. 31.

Georgia will be a key battleground in the 2022 midterm elections to determine which party controls the U.S. Senate. Republicans had long dominated statewide races in Georgia until 2020, when the state helped elect Joe Biden to the presidency and handed Democrats control of the Senate by electing Warnock and fellow Democrat Jon Ossoff in a January 2021 runoff.

Warnock, pastor of the Atlanta church where the Rev. Martin Luther King Jr. preached, became Georgia’s first Black U.S. senator. He has to defend his seat this fall after winning a special election in 2020 to fill the unexpired term of Republican Sen. Johnny Isakson, who stepped down because of failing health. Isakson died in December.

A statement by Warnock’s campaign said his fourth-quarter fundraising total was his biggest yet, boosted by 130,000 individual donors whose average contribution was $43. The campaign said Warnock ended the quarter with $23 million in cash on hand.

Though a political newcomer, Walker is among Georgia’s best-known sports heroes for his football career at the University of Georgia and in the NFL. He’s a Black conservative who has been endorsed by former President Donald Trump, a longtime friend, and Senate Minority Leader Mitch McConnell.

Walker’s campaign said more than 44,000 people in all 50 states made donations to the Republican candidate in the fourth-quarter. It said he has raised nearly $10 million total since entering the race in August but did not disclose how much cash he still had in the bank as of Dec. 31.

Further details won’t be available until Warnock and Walker file their quarterly fundraising reports with the Federal Election Commission. The deadline for Senate candidates is Monday.

Warnock raised more than $125 million for his 2020 Senate race, according to FEC reports. In the 2022 campaign cycle, he had raised $44 million as of Sept. 30.

In the GOP primary for the Senate seat, Walker faces at least three other Republicans who have declared candidacies. Gary Black serves as Georgia’s agriculture commissioner, Latham Saddler is a Navy veteran and former bank executive, and Kelvin King owns a construction company. Their campaigns have not yet filed fourth-quarter fundraising reports and did not immediately respond to email messages Wednesday.

Black has publicly questioned Walker’s fitness to serve in the Senate, citing his rival’s turbulent personal history. Walker has a lengthy history of mental health struggles, much of which he detailed in his autobiography. An investigation by The Associated Press in July revealed accusations that Walker repeatedly threatened his ex-wife’s life, exaggerated claims of financial success and alarmed business associates with unpredictable behavior.

A Walker campaign spokeswoman, Mallory Blount, dismissed Black’s criticism as a desperate move by a struggling candidate.