Former football star running back Herschel Walker on Wednesday officially declared his candidacy for the Senate in Georgia, jumping into a Republican primary race to challenge Democratic freshman Sen. Raphael Warnock in the 2022 midterm elections, in a crucial contest that could ultimately decide which party controls the majority in the chamber.

"Our country is at a crossroads, and I can’t sit on the sidelines anymore," Walker wrote in a statement.

"America is the greatest country in the world, but too many politicians in Washington are afraid to say that," Walker charged. "In the United States Senate, I will stand up for conservative values and get our country moving in the right direction. It is time to have leaders in Washington who will fight to protect the American Dream for everybody."

WALKER FILES TO SET UP SENATE CAMPAIGN IN GEORGIA

The announcement by the former star professional football player and college gridiron legend in the Peach State – Walker won a Heisman Trophy and helped steer the University of Georgia to a college football national championship – comes one day after he filed paperwork setting up his campaign. 

It also comes after months of support and encouragement to run for the Senate by former President Trump, his longtime friend - and amid concerns from some Republicans over the first-time candidate's ability to win a key seat for the GOP.

Then-President Donald Trump is greeted by NFL hall of fame member Herschel Walker during an event for black supporters at the Cobb Galleria Centre September 25, 2020, in Atlanta, Georgia. (Photo by Brendan Smialowski / AFP) (Photo by BRENDAN SMIALOWSKI/AFP via Getty Images)

Walker spotlighted his American story in his statement, noting that "where else could a poor kid from a small town in Georgia become valedictorian of his high school, earn the Heisman Trophy, play professional football, represent the United States in the Olympics, and become CEO of multiple companies? I have lived the American Dream, but I am concerned it is slipping away for many people."

Walker becomes the most prominent candidate to enter the race for the GOP Senate nomination in the Peach State. Among the others running are state Agriculture Commissioner Gary Black, who declared his candidacy in June, and two military veterans who are not as well-known, Latham Saddler and Kelvin King, who launched campaigns earlier this year.

Former Sen. Kelly Loeffler, who narrowly lost to Warnock in one of the two Jan. 5 Senate runoff elections in Georgia, has not closed the door to a potential campaign. Loeffler told Fox News in June that "I have not ruled anything out." Former Sen. David Perdue, who narrowly lost to now-Sen. Jon Ossoff in the state’s other runoff election in January, earlier this year said he was passing on making a 2022 bid.

Despite the increasingly crowded field, Walker enters the race at the clear frontrunner, thanks to his name recognition and the support from Trump, who seven months removed from the White House remains very popular and influential with Republican voters as he continues to play a kingmaker’s role in GOP politics and repeatedly flirts another presidential run in 2024.

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Walker, whose relationship with the former president goes back to his days playing for the Trump-owned New Jersey Generals USFL football team in the 1980s, was a major Trump supporter and surrogate in last year’s election.

"Wouldn’t it be great if the legendary Herschel Walker ran for the United States Senate in Georgia?" Trump wrote in a statement in March. "He would be unstoppable, just like he was when he played for the Georgia Bulldogs, and in the NFL. He is also a GREAT person. Run, Herschel, Run!" 

A poll released by Trump’s political action committee last week indicated that Walker would enter the Senate Republican primary far ahead his rivals.

The National Republican Senatorial Committee (NRSC), which remains neutral in Senate primaries with no incumbents in the race, welcomed Walker to the primary battle. 

"Herschel Walker is a great American and a great Republican," NRSC communications director Chris Hartline noted."

He added that Walker "will join a strong group of Republican candidates and be a formidable candidate. Georgia Republicans will have a spirited primary. We’re confident that whoever wins the primary will be well-positioned to beat Chuck Schumer and Bernie Sanders’ favorite Democrat, Raphael Warnock." 

REPUBLICANS RAISE CONCERNS OVER A WALKER SENATE RUN

But support for Walker is far from uniform across the party, with some Republicans for months expressing reservations over his looming candidacy.

Walker, as a first-time candidate, is untested under fire on the campaign trail and has not made it clear where he stands on many key issues. And he comes with plenty of political baggage that could give his opponents ammunition. He’s also for years openly discussed his struggles with a mental illness known as dissociative identity disorder. Walker spotlighted his mental health challenges in a 2008 book, writing that he was able to overcome his multiple personalities with therapy and his faith in Christianity.

Walker’s also been accused by his ex-wife of being "physically abusive." She’s alleged that he showed "extremely threatening behavior" towards her. And the Associated Press reported last month that Walker had over inflated the success of one of his chicken distribution business. 

There are also issues with Walker’s residency. While he’s long been a resident of Texas, Walker last week changed his voter registration to Georgia, using a home his wife Julie Blanchard owns in Atlanta as his address. State election officials earlier this month began investigating Blanchard for voting in Georgia in last year’s elections, even though her residency appeared to be in Texas at the time, according to a report from the Atlanta Journal Constitution.

Though he has Trump’s backing, Republicans close to longtime Senate GOP leader Mitch McConnell are privately expressing concerns whether Walker is ready for the rigors of a high-profile Senate campaign. Sources tell Fox News they’re specifically concerned about the troubling reports detailing Walker’s violent history that Democrats will certainly exploit if Walker wins next year’s GOP nomination.

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Some Republicans in Georgia are also raising concerns.

"He will need to show that he is a conservative," former Rep. Doug Collins, a Trump ally, said this summer on his radio program. 

"I have never heard Herschel Walker’s position on pro-life. I haven’t," said Collins, who came in third behind Warnock and Loeffler in a large field of candidates in November’s special election and who briefly mulled a 2022 run before ruling it out. "I’ve never heard his position on gun control. I’ve never heard his position on a lot of these issues that are conservative issues."

And some other Georgia Republicans are worried about a possible political train wreck as Walker faces incoming fire in the weeks and months ahead.

A Peach State based Republican strategist who asked to remain anonymous to speak more freely told Fox News last month that "we don’t know what a Herschel Walker candidacy looks like. What type of a candidate is he going to be? How is he going to handle being thrown into the fire? Is he going to be quick on his feet?"

And pointing to Walker’s well-publicized battle with mental illness, the strategist said, "He either he deals with those issues well and grows, or he struggles with explaining some of the issues that were in his book and he decides this isn’t for him."

As the GOP aims to win back the Senate majority they lost in January when the Democrats narrowly swept Georgia’s twin Senate runoff elections, they’re playing plenty of defense, defending 20 of the 34 seats up for grabs, including five open seats – with two of them in the crucial battlegrounds of Pennsylvania and North Carolina.

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But they also see opportunities to flip blue seats red in four states, including Georgia. And they view Warnock as one of the most vulnerable Democrats running for reelection in 2022. 

Warnock defeated Loeffler, who was appointed by GOP Gov. Brian Kemp, by a razor-thin margin on Jan. 5, to serve the final two years of the term of former GOP Sen. Johnny Isakson, who resigned in 2019 due to health reasons. But defeating Warnock won’t  be easy, as Georgia’s first Black senator has set fundraising records since taking office.

Fox News' Jason Donner contributed to this report