Vulnerable Democratic Sen. Jon Tester is trailing Republican candidate Tim Sheehy in Montana’s contested race which could flip control of the Senate to the GOP, according to an AARP poll from Thursday.

In a head-to-head race, Sheehy leads by six points at 51% while Tester is behind at 45%, according to the poll. In a four-way race, Sheehy’s lead over Tester increases to eight points with the candidates polling at 49% and 41% respectively, while Libertarian candidate Sid Daoud and Green Party candidate Michael Downey brought in 4% and 1%.

“Montanans are ready to make a change and fire Jon Tester–the number-one recipient of lobbyist cash–who votes 95% of the time for the disastrous Biden-Harris agenda that gave us reckless spending, record inflation, and open borders,” a spokesperson for Sheehy’s campaign told the Daily Caller News Foundation. “Jon Tester knows he is losing this race, which is why he will continue to stoop so low, because desperate men do desperate things, and now we need every supporter to vote so we win big and retire Jon Tester for good!”

Sheehy, who formerly served as a Navy SEAL and received a Purple Heart for his service in Iraq and Afghanistan, was endorsed by former President Donald Trump in February. Trump’s endorsement for Sheehy took place the same day Republican Rep. Matt Rosendale announced his candidacy for Senate, but he ended up dropping out less than a week later.

“I also respect Matt Rosendale, and was very happy to Endorse him in the past – and will Endorse him again in the future should he decide to change course and run for his Congressional Seat,” Trump said in a Truth Social post on Feb. 9. “But in this instance, Tim is the candidate who is currently best-positioned to DEFEAT Lazy Jon Tester, and Regain the Republican Majority in the United States Senate. Tim is a Political Outsider, Strong on the Border, the Military/Vets, and our constantly under siege Second Amendment. He will stand tall in the fight against the Radical Left Democrats, who are Destroying our Country. Also, he is far more likely to Defeat Lazy Jon. America First Patriot Tim Sheehy has my Complete and Total Endorsement!”

While Republicans account for nearly 40% of the likely voters in Montana, Democrats only account for about a quarter, according to the poll. This electorally disadvantages Tester who will need to get a boost from independent voters if the incumbent wants to secure his reelection.

Tester has held his seat in the red state since he was first narrowly elected in 2006 against Republican incumbent Conrad Burns. He won reelection in 2012 against U.S. Representative Denny Rehberg and in 2018 against Rosendale, although both times by a slim margin.

Tester’s campaign ads have aimed to appeal to Montana voters by claiming to have “worked with Trump” and that he has “stood up to Biden” during his term, saying he has worked to cut back spending and secure the border.

“I don’t look like folks in Washington, and that’s fine with me,” Tester said in the ad. “All I care about is defending Montana.”

The AARP poll was conducted from Aug. 25 to Aug. 29 surveying 1,064 likely Montana voters with a margin of error of 3.5 percentage points.

Tester’s campaign did not immediately respond to a request for comment from the Daily Caller News Foundation.