West Virginia Gov. Jim Justice (R) filed paperwork Thursday to run for the state’s Senate seat with Sen. Joe Manchin (D-W.Va.) up for reelection in 2024.

The move puts the West Virginia Republican one step closer toward officially launching a Senate campaign for Manchin’s seat. Justice is expected to officially launch his campaign for Senate later Thursday following months of speculation. 

Justice, 72, is looking to flip Manchin’s seat in the Senate, jeopardizing the Democrats’ already slim majority in the upper chamber.

Manchin has yet to announce whether he will seek reelection to his Senate seat. He’s also not completely ruled out a White House run.

Justice has served as the governor of West Virginia since 2017 and will join Rep. Alex Mooney (R-W.Va.) in the GOP primary. Mooney launched his Senate campaign last year. A third candidate, Chris Rose — a Trump-aligned fourth generation coal miner — has also launched a bid in the GOP primary.

Mooney told the MetroNews “Talkline” show earlier this week that he is the “only conservative” in the race and that Justice is a “RINO,” meaning Republican in Name Only. Mooney might be alluding to the fact that Justice switched his party affiliation in 2017 from Democrat to Republican. 

Manchin, 75, is one of the most vulnerable Democrats up for reelection in 2024 as one of three incumbents situated in states that former President Trump won in 2020. Sens. Jon Tester (R-Mont.) and Sherrod Brown (D-Ohio) are also up for reelection in states Trump won in the last presidential election.

Manchin has held his seat since 2010, following six years in the governor’s office. At times he’s been a thorn in the side of his party — he’s bucked Democrats on issues like climate change, President Biden’s “Build Back Better” legislation and opposing reforming the filibuster.

Polling commissioned by the Senate Leadership Fund, a super PAC aligned with Senate Minority Leader Mitch McConnell (R-Ky.), suggested that Justice was best positioned among several hypothetical primary challengers, including Mooney and state Attorney General Patrick Morrisey (R) to win against Manchin. Since the release of the polling, Morrisey announced a run for governor. 

A recent Morning Consult survey found that more West Virginians — 66 percent — approve of Justice over Manchin, who received 38 percent support. 

Justice is expected to make his campaign announcement at The Greenbrier, a resort in West Virginia owned by the governor.

The livestream link for his announcement is connected to a YouTube Channel for “Jim Justice for U.S. Senate.” The title of the livestream is called “Gov. Justice and Babydog make Special Announcement.” Babydog is the name of Justice’s pet bulldog.

Updated: 11:16 a.m.