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(WASHINGTON) — West Virginia Gov. Jim Justice is set to announce a Senate campaign on Thursday afternoon, setting up a potential challenge to incumbent Democratic Sen. Joe Manchin, who has not yet said if he’ll run for reelection.

If Justice and Manchin square-off next year, the outcome could determine the balance of power in the Senate, which is currently held by Democrats, 51-49.

A senior GOP aide confirmed that Justice plans to launch his Senate bid at the Greenbriar, a West Virginia luxury resort that he owns. Justice also filed paperwork with the Federal Election Commission to form his campaign. A spokesperson for him did not immediately respond to a request for comment.

He will join Rep. Alex Mooney in the GOP primary.

Manchin’s seat is at the top of Senate Republicans’ target list, along with Democratic-held seats in Montana and Ohio, and Justice was a top recruit for party leaders. Source familiar with GOP outreach told ABC News that both Senate Minority Leader Mitch McConnell, R-Ky., and Sen. Steve Daines, R-Mont., the chair of the National Republican Senatorial Committee, both spoke with Justice to encourage him to run.

Manchin has said he won’t decide until December whether or not he’ll run for reelection, retire or even run for president. However, he’s believed to be the only Democrat who can realistically retain the Senate seat — given his deep ties to West Virginia and history of success there, even as the state increasingly favors Republicans and twice voted for Donald Trump by yawning margins.

Manchin is one of the most centrist Democrats in Congress and has been critical of President Joe Biden, even threatening to repeal one of his signature pieces of legislation, the Inflation Reduction Act, over a dispute about the use of tax credits. Manchin has more than $9 million in the bank before he starts campaigning in earnest, if he chooses to run.

“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,” he said in a statement on Tuesday, prior to Justice’s announcement. “But make no mistake, I will win any race I enter.”

Manchin’s allies echoed his confidence, either against Justice, who switched parties from being a Democrat during a campaign rally with then-President Trump in 2017, less than a year after being elected governor — a move Manchin lambasted at the time — or Mooney, a firebrand who has faced carpetbagger attacks over his moving from Maryland.

“All Joe Manchin knows how to do is win,” Jonathan Kott, a lobbyist and former top Manchin aide, told ABC News.

Still, Justice’s announcement marks a coup for McConnell and Daines, who have voiced frustration over “candidate quality” issues in the 2022 midterms that they suggested cost them winnable Senate seats.

McConnell aggressively but unsuccessfully sought to recruit popular Republican governors to run for Senate in Arizona, Maryland and New Hampshire. Instead, less experienced and more controversial candidates ended up losing key races, including Blake Masters in Arizona and Herschel Walker in Georgia.

To reach a potential head-to-head with Manchin, Justice will first have to defeat Mooney in the GOP primary, who has swiped at the two-term governor over his past party switch.

“You want a proven conservative, I’m your guy. I have a voting record you can look at. You want someone who’s more of a liberal Republican, there’s Jim Justice,” Mooney said on MetroNews’ “Topline” program.

Both Justice and Mooney are likely to leverage their ties to Trump and a flood of resources.

Justice, a coal magnate, is independently wealthy and could pour millions into his bid. Mooney, meanwhile, has the backing of the anti-tax Club for Growth.

The Senate Leadership Fund, the prominent super PAC aligned with McConnell, put out internal polling earlier this year showing Manchin losing to Justice but beating Mooney in a primary, an early signal of muscular involvement to come from the group. Meanwhile, the Club for Growth has already committed $10 million to support Mooney.

Democrats are banking on the GOP primary drawing blood from whoever ultimately wins the nomination.

“Whichever candidate manages to hobble out of their intraparty battle will be damaged and out of step with the voters who will decide the general election,” said Democratic Senatorial Campaign Committee spokesperson Amanda Sherman Baity.

Still, whoever the nominee is will have a hefty partisan advantage in West Virginia, where the Democratic Party outside of Manchin is virtually nonexistent.

When asked about how Manchin would stack up against Justice, former Rep. Nick Rahall, a surrogate during Manchin’s 2018 campaign, texted ABC News that the race “would be a nailbiter.”

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