Republican hopes of taking control of the U.S. Senate in November could hinge on former football star Herschel Walker, a first-time candidate endorsed by Donald Trump, whose campaign appears to be lagging behind other Republicans in Georgia.

A sports legend, the 60-year-old Walker secured the Republican nomination to run for the Senate for the state in May, seeing off five contenders. Republicans hoped his popularity and name recognition would translate into victory in what is likely to be a close race.

But he has been trailing Democratic Senator Raphael Warnock in most opinion polls, his campaign rocked by repeated policy gaffes and a string of controversies about his past, including allegations of domestic violence.

Walker is one of a handful of Trump-endorsed first-time Republican Senate candidates, also including TV personality Mehmet Oz in Pennsylvania and author J.D. Vance in Ohio, who even senior Republicans say are weighing on the party's changes of recapturing Senate control.

Senate Republican leader Mitch McConnell, without naming individuals, has cited "candidate quality" as a reason why Republicans may struggle to capture the Senate, putting his party's odds of winning a Senate majority at 50-50.

Analysts say Walker has made himself an easy target for political attacks, with disjointed comments on issues from COVID-19 to climate. For instance, he attacked the recently-passed $430 billion climate and drug bill on Sunday, saying a lot of the money is "going to trees" and asking, according to the Atlanta Journal-Constitution, "Don't we have enough trees around here?"

"Every time he opens his mouth about a policy issue, it sounds like a word salad. It's very convoluted and doesn't make sense sometimes," said Trey Hood, a political science professor at the University of Georgia.

The Republican Accountability political action committee, run by anti-Trump Republicans, has tried to put domestic violence allegations front and center in the campaign. It released a 30-second ad in which Walker's ex-wife Cindy DeAngelis Grossman says "he held the gun to my temple and said he was going to blow my brains out."

Walker responded with his own video, saying Grossman's comments were taken out of context but that he was "glad they did this ad, because it gives me an opportunity to end the stigma around mental health."

The Walker campaign and local Republican Party leaders say the former sports star has been the target of unfair news coverage, insisting that his interactions with voters at campaign events have been overwhelmingly successful.

"The whole situation is quite aggravating to me, because Herschel Walker is an extremely intelligent man who has a full grasp of the issues," said Salleigh Grubbs, who chairs the Republican Party in Cobb County, just outside Atlanta.

With the 100-seat Senate currently split 50-50, Republicans need only a net one-seat gain to take the majority.

Georgia was Republican territory until Biden won the state by a thin margin in 2020, and Warnock and fellow Democratic Senator Jon Ossoff unseated two Republican incumbents in a 2021 run-off.

Opinion polls suggest the gap between Walker and Warnock is very narrow, and some have had Walker ahead. But he is considerably less popular in surveys than other Georgia Republicans, including Governor Brian Kemp, who is up for re-election this year. That, analysts said, suggests that some Republican voters who cast ballots for Kemp could just opt not to vote for a Senate candidate -- or to back Warnock instead.

Warnock was well known in the state, too, before he was elected to the Senate, as senior pastor of Atlanta's Ebenezer Baptist Church, where slain civil rights leader Martin Luther King once preached. Strategists say that could appeal to Georgia's large Christian electorate.

Warnock has also used recent Democratic legislative victories to fortify his appeal to voters.

"Reverend Warnock is focused on fighting for hardworking Georgia families, leading the effort to successfully cap the cost of prescription drugs for seniors, protect Georgia jobs and hold corporations accountable for price gouging," Warnock campaign communications director Meredith Brasher said in a statement.

Democratic strategists expect Warnock to emphasize his policy message to try to overcome Walker's name recognition as a former NFL player who led the University of Georgia to its first national football title in 1980.

Both Walker and Warnock are Black. And Atlanta-based Democratic strategist Fred Hicks said Warnock could improve his ground game against Walker by driving up turnout among Black male voters with concrete appeals on policy issues including jobs and healthcare.

But Republicans argue that the close poll numbers bode well for Walker, given the controversies and political attacks he has weathered.

"Beating an incumbent senator is never easy. But Herschel is a good candidate and is he going to win," said Walker campaign communications director Will Kiley.

The Georgia Senate race is already expected to be the nation's most expensive, according to research firm AdImpact, which forecasts $276 million in ad spending. Spending could intensify even further if the Nov. 8 election proves inconclusive and a Georgia run-off becomes the deciding factor for Senate control.