• West Virginia's Republican governor, Jim Justice, filed official paperwork to kick off a 2024 campaign for the U.S. Senate seat currently held by incumbent Democratic Sen. Joe Manchin.
• The long-anticipated move by Justice could further imperil Democrats' efforts to keep their slim majority in the Senate.
• Manchin, one of the chamber's most conservative Democrats, has said he won't decide whether to run for reelection until closer to the end of the year.
• "I will win any race I enter," Manchin said following news of Justice's Senate campaign.

West Virginia Republican governor Jim Justice announced his 2024 campaign for the U.S. Senate seat currently held by incumbent Democratic Sen. Joe Manchin on Thursday.

The long-anticipated move by Justice, who switched parties in 2017 and has since become one of the red state's most popular politicians, could further imperil Democrats' efforts to keep their slim majority in the Senate.

"I hate like crazy it's taken this long to make a decision," Justice said at a campaign kickoff event Thursday at The Greenbrier, his luxury hotel in White Sulphur Springs, West Virginia.

The governor touted his conservative record on issues including abortion laws — "the toughest of the toughest" — and school choice.

Justice sat on a wooden stool as he addressed a crowd of his supporters, while Babydog, the governor's 3½-year-old English bulldog and de facto campaign surrogate, was seated next to him in a plush red armchair.

Manchin, one of the chamber's most conservative Democrats, has said he won't decide whether to run for reelection until closer to the end of the year, regardless of Justice's plans. His seat is considered one of the most winnable for Republicans in next year's election.

"I am laser focused on doing the job West Virginians elected me to do – lowering healthcare costs, protecting Social Security and Medicare, shoring up American energy security and getting our fiscal house in order," Manchin said in a statement Thursday morning after news of Justice's Senate bid.

"But make no mistake, I will win any race I enter," Manchin said.

The senator told reporters later Thursday morning, "Let the games begin."

While Manchin has taken an adversarial tack against much of his own party in recent months, he could be their best hope of holding onto their majority in 2024, when they will defend 23 of the cycle's 34 Senate seats up for grabs.

If Manchin decides not to run for a third term, Democrats are widely expected to lose the seat to whichever Republican nominee emerges from West Virginia's Senate primary. Rep. Alex Mooney, R-W.Va., who was backed by former President Donald Trump in his most recent House election, has already jumped into the Senate race.

"Jim Justice is just another Joe Manchin," Mooney's campaign manager, John Findlay, said in a statement ahead of the governor's announcement. The statement accused Justice of backing the "largest tax hike in West Virginia's history," contrasting Justice's own boasts about signing the state's largest-ever tax cut last month.

Justice stood alongside Trump when he announced that he would switch to the Republican Party, and he has spoken to the former president by phone in advance of his Senate campaign launch, NBC News reported. A Trump campaign spokesman did not immediately respond to a request for comment.

Victory is hardly a guarantee for Manchin if he does try to hold onto the seat. Despite his incumbent advantage, his hefty war chest and his reputation for breaking with fellow Democrats, Manchin's party affiliation may too great an obstacle to overcome in a state that voted for Trump by nearly 40 points in 2020.

Manchin won his last Senate race in 2018 by just 3 percentage points. With his seat under threat, Manchin has appeared increasingly critical of President Joe Biden and his fellow Democrats, even vowing to vote to repeal the Inflation Reduction Act, Biden's signature spending bill that he helped pass.

The governor, who is term limited in that role, had been strongly encouraged to run for Senate by top Republicans, including Sen. Steve Daines of Montana, chair of the National Republican Senatorial Committee, and Senate Minority Leader Mitch McConnell of Kentucky.

"Jim Justice is a proven winner whose record of creating jobs, cutting taxes, and fighting for conservative values has made him one of the most popular governors in the country," Daines said in a statement.

Justice's choice of venue for his announcement is notable: The governor's blending of his political and business activities came under scrutiny in a 2019 ProPublica investigation. Manchin, in that report, criticized Justice's use of his resort, saying, "It's called public service, not self-service."

Justice, who is also celebrating his 72nd birthday on Thursday, was joined at The Greenbrier by a crowd of family, friends and others from across the state.

Sen. Shelley Moore Capito, West Virginia's Republican junior senator, and Sen. Lindsey Graham, R-S.C., lauded Justice before he took the stage.

"Jim Justice knows how to deliver for people he represents. He's done it in your state," Graham said. "He will protect your guns, and he's good with your wallet."

Manchin has said that he would want to preserve his "personal relationship and friendship" with Justice if he were to face him in the general election. But Justice can be expected to contrast himself and his record with both Manchin and Mooney as he hits the campaign primary trail.