Senator Tester, one of the top Republican targets in the Senate in 2024, is getting his first challenger, a former Navy SEAL officer, Tim Sheehy, in what is set to become one of the most hotly contested Senate races of 2024.

Mr. Sheehy is entering what is expected to be a marquee Senate race in 2024, as Republicans attempt to unseat Mr. Tester.

Despite Mr. Tester’s enduring popularity, he is seen as one of the most vulnerable Democratic senators up for re-election because he represents a state that has not voted for a Democrat on the presidential level since 1992.

An associate editor at Sabato’s Crystal Ball at the University of Virginia Center for Politics, Miles Coleman, tells the Sun that “this is going to be one of the top-tier races of the cycle — every time Tester comes up, he manages to get by, but Republicans are hoping that streak will finally end in 2024.”

In Mr. Sheehy’s announcement video, he recalled how he felt on September 11, 2001 and how the event was a motivation for him to enter the military, where he met his wife.

“That fateful day motivated me to serve my nation as a Navy SEAL,” Mr. Sheehy said. “I’m Tim Sheehy. Whether it was in war or in business I see problems and solve them. America needs conservative leaders who love our country and that’s why I’m running for United States Senate.”

His announcement video also touted his experience as a businessman claiming to have created one of “the largest aerial firefighting companies in America” and to have created over 200 jobs in Montana.

Although Mr. Sheehy — or whichever Republican wins the nomination in 2024 — might seem to have the wind at his back running against a Democratic Senator in a ruby red state, there’s a catch.

Mr. Tester is among America’s most popular senators. A poll from Morning Consult in April found that Mr. Tester was the ninth most popular senator in the country, with a 58 percent approval rating and a 38 percent disapproval rating in his state.

Mr. Tester was also the most popular Democratic senator from a state dominated by the opposing party. In 2020, President Trump won Montana by over 16 points. 

Mr. Tester has held onto his seat since he was first elected in 2006, winning re-election in 2012 and 2018, both favorable years for Democrats.

In 2018, the Republican effort to unseat Mr. Tester and the Democratic response broke the state record for cash spent on a single election. All told, more than $60 million was spent on the race.

“Over the years, Tester has tried to cultivate a down-to-home image, often pointing to his position as the Senate’s only dirt farmer,” Mr. Coleman tells the Sun. “In 2018, there was a parochial element working in his favor.Matt Rosendale spent most of his life in Maryland, so Tester tried to make the case that his opponent wasn’t ‘one of us.’”

Montana Democrats have already begun leveling criticism against Mr. Sheehy, with spokeswoman Monica Robinson saying that “Jon Tester has farm equipment that’s been in Montana longer than Tim Sheehy” in a statement Tuesday.

“The last thing Montanans want in a senator is an out-of-state transplant recruited by Mitch McConnell and DC Lobbyists,” Ms. Robinson said.

In 2024, Republicans are expected to once again launch a fierce effort in the state, and Mr. Sheehy isn’t the only one hoping to get the nomination. Mr. Tester’s 2018 opponent, Congressman Matt Rosendale, is also expected to throw his hat in the ring. According to reporting by Politico, Mr. Rosendale has been floating the idea to his colleagues in Congress.

Although Mr. Sheehy may have entered the race before Mr. Rosendale, a Public Policy Survey circulated last week suggests that Mr. Rosendale is the man to beat in the GOP primary.

The survey found that while 77 percent of Montanans didn’t know who Mr. Sheehy is, 67 percent have a favorable opinion of Mr. Rosendale. In a head-to-head matchup, the poll found Mr. Rosendale leads Mr. Sheehy 64 percent to 10 percent. The poll did not survey opinions of Mr. Tester.

Complicating matters is the fact that the current chair of the National Republican Senatorial Committee, Senator Daines, is the other senator from Montana, and it’s clear he favors Mr. Rosendale over Mr. Sheehy.

“He’s taking a look at the race,” Mr. Dains told Politico on the matter. “He’s giving it careful consideration.”

In Mr. Coleman’s opinion, either candidate could potentially defeat Mr. Tester but they both have their downsides as well, with Mr. Sheehy being unknown and Mr. Rosendale already having lost to Mr. Tester.

“On paper, Sheehy seems like a credible candidate, and has an attractive biography as a Navy SEAL (a growing bloc in Congress) but is basically untested when it comes to running for office,” Mr. Coleman says. “Rosendale has the benefit of being in office and perhaps has more credibility with the grassroots — but he has a reputation as a bit of a rabble-rouser.”