Republican Tim Sheehy has built up a steady polling lead against Democratic Senator Jon Tester in what may become the most important Senate race of the 2024 election.

Montana, usually a ruby-red state, is home to one of the most competitive Senate elections of the cycle. Tester, a centrist Democrat who has served as senator since 2006, has outrun other Democrats in the state in the past, and the party’s majority may hinge on his ability to win in November.

But a flurry of recent polls showing Sheehy, a former Navy SEAL officer and businessman, in the lead has sparked concerns about whether he can win in Montana this year. Turnout is expected to be high in a state former President Donald Trump will almost certainly win. Montana’s history of ticket-splitting has also ebbed in recent years.

While Sheehy has benefitted from strong polling numbers, Tester still holds a fundraising advantage.

So far this campaign, Tester has raised about $43 million, while Sheehy has raised nearly $14 million, according to data from the Federal Elections Commission (FEC). Meanwhile, Tester has spent more than $32.6 million, while Sheehy has spent over $10.6 million, the nonprofit OpenSecrets reported.

At the end of June, Tester had about $10.9 million in the bank, compared to $1.7 million for Sheehy, according to the FEC. Fundraising is crucial for any Senate candidate, but Montana is a smaller, generally less expensive state with fewer media markets than other key Senate races in states like Pennsylvania or Texas.

The amount of money both parties pour into the race speaks to its importance this year. Democrats currently hold a 51-49 Senate majority and are expected to lose at least the seat vacated by West Virginia Senator Joe Manchin.

This means Democrats must win every other seat they currently hold or flip one elsewhere to retain their majority in what has been viewed as a particularly challenging map in November. Montana is considered the tipping point for Senate control, with Ohio being another Democratic-held seat in a Republican-leaning state viewed as a potential GOP flip.

Tester continued to outraise Sheehy in the second quarter, bringing in $10.5 million to Sheehy’s $5.3 million, according to the Helena-based Independent Record.

Outside PACs have also spent tens of millions of dollars on the race, according to OpenSecrets.

GOP-supporting PACs have spent more than $13 million on advertisements supporting Sheehy and more than $30 million opposing Tester. Conversely, Democratic-leaning PACs have spent $3.5 million in support of Tester and nearly $31 million opposing Sheehy, according to the nonprofit.

The Last Best Place PAC, reported by HuffPost to be affiliated with Democratic leadership, has been the top outside spender in the race, pouring in $19 million. Meanwhile, the GOP-aligned More Jobs, Less Government PAC spent $18.8 million on the election, according to OpenSecrets.

Tester spokesperson Monica Robinson told Newsweek on Friday that the senator is “no stranger to tough races.”

“He’s won three in a row because he has a strong coalition of support across the state, including independent voters and Republicans, and he has a record of delivering for Montana. Montanans know that the dirt farmer from Big Sandy is the best choice to defend Montana – not the multimillionaire out-of-stater Tim Sheehy, who doesn’t understand our way of life and is changing Montana for the worse,” Robinson said.

Newsweek also reached out to the Sheehy campaign for comment via email.

FiveThirtyEight’s polling aggregate gave Sheehy a 3.7-point advantage over Tester on Thursday following weeks of strong Republican polling in the state.

An RMG Research/Napolitan Institute survey conducted among 491 likely voters from September 12 to September 19 showed Sheehy up seven points (50 percent to 43 percent).

That pollster showed Tester with a lead as recently as last month, with an August 6 to August 14 poll among 540 registered voters showing Tester up five points (49 percent to 44 percent).

A Fabrizio Ward/David Binder Research/AARP poll, which surveyed 600 likely voters from August 25 to August 29, showed Sheehy up six points in a head-to-head race (51 percent to 45 percent).

Elsewhere, an American Pulse Research & Polling/KULR-TV poll showed Sheehy with a 6-point lead over Tester (51 percent to 45 percent). It surveyed 538 registered voters from August 10 to August 12.

Sheehy, endorsed by Trump, has faced scrutiny after a Native American news publication released audio recordings allegedly of Sheehy using stereotypes about Indigenous people. His spokesperson told the Associated Press, “What folks are insinuating about him, that’s just not who he is.”

Following the spate of polls showing Sheehy with a lead, Democrats announced plans for new investments in the Florida and Texas Senate races this week, suggesting they may see the Montana race as increasingly out of reach.

Even though Republican incumbent Senators Ted Cruz and Rick Scott have been viewed as favorites, recent polls showed the states could be closer than Montana as democratic challengers Representative Colin Allred and former Representative Debbie Mucarsel-Powell gain ground.

The Cook Political Report rates Montana’s Senate race as “Lean Republican,” meaning it is “considered competitive,” but the GOP “has an advantage.”

Sabato’s Crystal Ball also reclassified the race from “toss-up” to “Lean Republican” on September 6, with forecaster Kyle Kondik writing that “history and recent trends are just not on Tester’s side.”

“He is one of a relatively small number of partisan outliers in either chamber of Congress, holding a Senate seat that the other party won by 16 points in the most recent presidential election,” Kondik wrote. “Many of Tester’s red-state Democratic colleagues have lost or retired in recent years, and it is a credit to his abilities that he has won 3 Senate elections in a state that is otherwise clearly Republican.”

Update 9/27/24, 5:43 p.m. ET: This article was updated with comment from Monica Robinson.