The top Republican candidates for U.S. Senate in Georgia haven’t laid a glove on Herschel Walker, the football icon edging toward a possible run for the office. Until now.

Agriculture Secretary Gary Black, the most prominent Republican in the race, released a digital ad Monday mocking Walker’s flirtation with entering the race from his home in Texas.

The ad pokes fun of a video posted on Walker’s social media that showed him in front of a car with a suspended Georgia license plate while he boasts he’s getting ready to “run with the big dogs.”

“I’m ready. I’ve been ready. And, Herschel, I already run with the big dogs,” Black said in the ad. “For fun, my ride’s a tractor. And I’ve had Georgia plates all my life.”

He’s the first of the trio of Republicans seeking to challenge Democratic U.S. Sen. Raphael Warnock to take a shot at Walker. And it’s the latest sign that Georgia Republicans are uneasy pinning their hopes on an untested candidate with a violent, erratic past.

It could be the beginning of a concerted effort by Black to show his tougher side as he races to position himself against Walker and fend off two other challengers: Military veterans Latham Saddler, the race’s leading fundraiser, and Kelvin King, a construction executive.

Black has assembled a team of campaign aides who aren’t afraid to throw an elbow. They’ve shown that while working for the likes of U.S. Rep. Doug Collins during his 2020 Senate bid and a string of longshot congressional candidates who successfully won tough races. Some cut their teeth in Sonny Perdue’s bare-knuckled 2002 bid for governor.

Their challenge is to show the edgier side of Black, a three-term agriculture commissioner perhaps best known in much of the state for his advocacy of the Georgia Grown farming initiative. In the weeks ahead, they’re likely to frame him as a budget-cutting enforcer charged with ensuring food safety and preventing animal cruelty. Campaign insiders see it as a “nice guy/tough guy” blend.

Before Monday, the three Senate contenders hadn’t taken direct aim at Walker, though they more subtly contrasted their records: a record in the armed forces or in public office, their ties to Georgia, and a willingness to engage grassroots voters on the campaign trail.

Meanwhile, a drumbeat of recent media reports have highlighted Walker’s exaggerated business dealings, his violent behavior, a growing chorus of Republicans worried by his potential candidacy and the revelation that he skipped the 2016 presidential election.

In a statement, Black called on Walker to get off the sidelines if he’s going to run.

“If my old schoolmate from UGA wants to join the conversation here in Georgia, I welcome hearing his ideas,” Black said. “But it takes more than pretending to change your car tags. Move here, pay taxes here, register and vote in some elections and learn what Georgians have on their minds.”