Former Gov. Nathan Deal endorsed Agriculture Commissioner Gary Black’s campaign for the U.S. Senate on Monday, making him the highest-profile Republican to pick sides in the unpredictable contest to take on Democratic incumbent Raphael Warnock.

The two-term governor’s endorsement of Black makes him a pioneer in the 2022 race. Most of the state’s Republican establishment has stayed on the sidelines as Georgia football icon Herschel Walker inches toward running for the seat with Donald Trump’s blessing.

Still, a growing number of state Republicans have expressed doubts about whether Walker is the best candidate to challenge Warnock. He hasn’t lived in Georgia in decades, his stances on key policy issues are largely unknown and he’s wrestled with violent bouts linked to mental illness.

Warnock’s strong fundraising numbers have only increased the pressure on Republicans. The Democrat has raised more than $12 million since his January runoff victory, and he boasts roughly $10.5 million in the bank for his campaign for a full six-year term.

While other senior Republicans passed on a race or decided to wait Walker out, Black entered the contest in June with a promise to unify a Georgia GOP shellacked by a string of statewide defeats in November and January. He said he’s planning to stay in the race even if Trump backs another candidate.

Black is not the only one who has made the leap. Military veteran Latham Saddler surprised many Republicans by announcing he’s raised more than $1.4 million for his Senate bid, a lofty sum for a first-time candidate. Kelvin King, another veteran, is also in the contest. And former U.S. Sen. Kelly Loeffler is among several Republicans who haven’t ruled out a run.

In his endorsement, Deal steered clear of mentioning Walker – or any other potential Senate candidates. Instead, Deal’s message focused on his friendship with Black and his experience in elected office as a three-term agriculture commissioner.

“We worked together for the entire time that I was governor. And he’s done a great job representing everyone in our state,” said Deal. “That’s the kind of leadership we need in Washington.”