Sen. Jon Tester and Republican challenger Tim Sheehy are facing off in Montana as the Democratic incumbent fights to hold onto his seat in the Senate in a race that’s key to determining which party controls the upper chamber. 

Considered the most endangered Democrat seeking reelection in the Senate this cycle, Tester, a moderate in deep-red Montana, has been under the political microscope for months as he campaigns to keep the seat he’s held for nearly two decades. Although the 68-year-old has fended off previous challenges, shifting demographics and political dynamics in the state appeared to enhance the pickup opportunity for Republicans in the 2024 election. 

Sheehy, a former Navy SEAL and founder of an aerial firefighting company, received his party’s backing as the candidate to take on Tester. The 38-year-old worked to draw a contrast with Tester, portraying himself as an outsider during the campaign while painting the Democrat as an establishment candidate with deep ties to Washington. He also touted bringing jobs to Montana with his business, which made him wealthy enough to help fund his campaign. 

Sheehy, who grew up in Minnesota, has faced criticism for lacking the deep roots that Tester has in the state. He has also faced questions about discrepancies in his story of how he sustained a gunshot wound. Meanwhile, Tester sought to portray his opponent as an out-of-touch carpetbagger, likening the GOP candidate to rich out-of-staters who have flocked to Montana in recent years. 

Tester is a third-generation Montana farmer. First elected to the Senate in 2006, his brand is well known in the state, and despite its more conservative politics, he’s won reelection twice as a moderate Democrat. 

But Montana’s political landscape has changed. In 2020, Donald Trump won Montana by more than 16 points, and trends suggest that an influx of new residents in the state is made up largely of Republicans. The state’s changing dynamics posed a serious hurdle for Tester — the sole Democrat serving in statewide office in Montana.

The Montana Senate seat is a key target for Republicans looking to build a GOP majority in the upper chamber. And it marks among the final Democratic holdouts in the Great Plains, and in red states more broadly. 

With a narrow 51-49 majority in the Senate, Democrats have little room for error. After Sen. Joe Manchin opted not to seek reelection, all but guaranteeing a GOP flip of his seat in West Virginia, Republicans looked to Tester’s seat as the next best opportunity to gain ground.