With all eyes on the conservative Democratic senator of West Virginia, Joe Manchin, two of the state’s most prominent Republicans, Governor Justice and Representative Alex Mooney, are gearing up for what could be a no-holds-barred election primary.

Whoever wins, Mr. Manchin, who’s yet to announce if he’s running, would face long odds in what’s become a deep red state. Control of the U.S. Senate could hang in the balance.

Mr. Manchin, 75, has been coy about his plans for 2024, possibly owing to his unfavorable poll numbers in the state or to his habit of announcing at the last possible moment, as he did when he made official his 2018 run in January of that year.

He has also fed speculation that he may run for governor or as an independent candidate for president, telling reporters last week, “I lost one race in 1996. I made a vow that I’d never lose another race.

“I am laser-focused on doing the job West Virginians elected me to do,” Mr. Manchin said. “But make no mistake, I will win any race I enter.”

Mr. Justice is clearly aware of Mr. Manchin’s reluctance to enter a race against him, as polling has consistently shown that the governor would be the likely victor of that race.

“Joe knows he can’t beat me,” Mr. Justice told WRNR, a radio station out of Martinsburg, in the Eastern Panhandle of West Virginia. “All kinds of different senators say ‘If you’re in it, Joe won’t run.’”

According to an April Morning Consult poll, 66 percent of registered West Virginia voters approve of how Mr. Justice is doing his job as governor, compared to 38 percent who approve of how Mr. Manchin is performing in the Senate. However much Mr. Manchin has tormented President Biden and his more progressive Democratic colleagues with his relatively conservative positions, he’s still a Democrat in an overwhelmingly Republican state that President Trump won by 39 points in 2020.

There are also signs that Senate Republicans are aware of Mr. Justice’s chances against Mr. Manchin and are backing him in the increasingly personal primary, even if they aren’t explicitly supporting him over Mr. Mooney yet.

At Mr. Justice’s announcement at the Greenbrier last week, Senators Graham and Capito made an unusual show of support for one candidate over another early in the primary.

“In 2024, during the election season, it is going to revolve around us, because this is about taking back the majority in the United States Senate,” Ms. Capito said. “Jim is going to be a great part of that and a great partner.”

Mr. Justice also appears to be the Senate minority leader’s favorite candidate, if for no other reason than that he stands the best chance of defeating Mr. Manchin.

The Senate Leadership Fund commissioned a poll in February that suggested that Mr. Justice was likely to defeat Mr. Manchin, and was the strongest of the current GOP primary candidates in that matchup.

An associate editor at Sabato’s Crystal Ball at the University of Virginia’s Center for Politics, J. Miles Coleman, explains to the Sun, “Essentially, [Senator] McConnell wants to get a Republican butt in that seat with as little drama or risk as possible.”

Mr. Mooney, backed by the influential Club for Growth, isn’t about to go down without a fight. He has already launched a scorched-earth campaign against Mr. Justice, attacking him as a “RINO,” or Republican in name only, because of his past Democratic Party affiliation.

“Jim Justice has a liberal record and Republican primary voters will soon see that he is nothing but a Democrat in sheep’s clothing,” Mr. Mooney said. “The D.C. establishment can call Justice a frontrunner all they want. Alex Mooney is the only true conservative in this race and the only candidate that will beat Joe Manchin next November.”

The attacks have become personal, with one website managed by Mr. Mooney’s campaign calling Mr. Justice a “phony” and claiming Mr. Justice opposes a “Right to Work” law in the state. It also claims that Mr. Justice sided with President Biden on the American Rescue Act and what the webpage calls the “non-infrastructure bill.”

In the interview on WRNR, Mr. Justice defended himself, saying that he wanted to focus on the issues in the race but wouldn’t let Mr. Mooney’s escalating attacks go without rebuttal.

“We want to be respectful,” Mr. Justice said. “Listen, I’m not one to start stuff, but I’m not going to sit idly by and listen to people’s — just garbage.”

According to Mr. Coleman, Mr. Mooney — originally from Washington, D.C. — is likely to face the “carpetbagger” label that has followed him throughout his political career, both in the primary and the general if he makes it there.

The Democratic Senatorial Campaign Committee, taking note of the primary, is already sharpening its knives, with a spokeswoman, Amanda Sherman Baity, saying that the primary is getting “nastier by the day.”

“Whichever candidate manages to hobble out of their intraparty battle will be damaged and out of step with the West Virginia voters who will decide the general election,” Ms. Sherman Baity said.

Behind the increasingly personal rhetoric of the GOP primary, though, there is also a regional divide at play that could work to Mr. Mooney’s advantage.

Although Mr. Justice has won statewide elections before, and on both partys’ tickets, his base of support has in the past been in the historically coal-mining south, whereas Mr. Mooney’s support has been in the north, in the second district, which he represents.

“A regional divide like that may actually work in Mooney’s favor, as many voters in the southern coalfields are still registered Democrats, so they won’t be able to vote in a GOP primary,” Mr. Coleman tells the Sun. “That was something that worked against Evan Jenkins in the 2018 primary.”

Although Mr. Justice dismissed the issue as a potential problem for his campaign in the interview with WRNR, it was probably not an accident that he was appearing on a northern radio station out of Mr. Mooney’s district the day after his campaign announcement.

“Nobody knows Alex Mooney in the south,” Mr. Justice said. “From the standpoint of the north and the Eastern Panhandle I hope to goodness that I’ve had incredibly warm feelings about the votes in the eastern panhandle and the northern panhandle of the state.”

Mr. Mooney’s office did not immediately reply to a request for comment.