Senator Jon Tester is trailing Republican rival Tim Sheehy in Montana’s U.S. Senate race, a contest that could determine control of the chamber, according to a new poll released Sunday.

Just over a week until Election Day, which will determine who is in control Congress as well as the White House, the Senate most of it is playable, with razor-thin edges. The upper chamber is controlled by Democratsholding a narrow majority of 51 seats as four independent caucuses with the party, while republicans hold 49.

Tester, a Democrat first elected in 2006, faces a challenge for his seat from Donald Trump– said Republican businessman Sheehy. Tester is a three-term moderate senator, and his opponent, Sheehy, is a former Navy SEAL and entrepreneur.

Montana, traditionally a Republican-leaning state, is expected to easily support Trump in the presidential race, and therefore Tester should once again split voters’ tickets. The former president won Montana in 2020 by 16 points against the President Joe Biden.

An Emerson College/The Hill poll of 1,000 likely Montana voters, conducted Oct. 23-25, finds Sheehy with a 4 percentage point lead over Tester, 50 to 46 percent. Sheehy’s lead is outside the poll’s margin of error of plus or minus 3 percentage points and shows a tightening of the race from previous polls that had Sheehy ahead.

Three percent of respondents said they were undecided, and 2 percent were voting for someone else. Among undecided voters, Tester is gaining ground, with a combined Senate vote of 48 percent for Tester and 50.6 percent for Sheehy.

Republican and Democratic Senate candidates have similar favorability ratings in the state, with 48 percent of respondents having a somewhat favorable view of both.

“Race finds stark gender gap: Women trail Tester by about 14 points, 55 percent to 41 percent, while men trail Sheehy by 22 points, 59 percent to 37 percent,” Spencer Kimball , executive director of Emerson College Polling, said.

That poll finds an increase in Sheehy’s support from the August Emerson College Polling/The Hill poll of 1,000 likely voters, which found Sheehy at 48 percent to Tester’s 46 percent. The survey was conducted between August 5 and 6.

Newsweek filed a contact request form on Sheehy’s website for comment and emailed Tester’s campaign on Sunday.

However, among other recent polls, the latest Emerson College Polling/The Hill poll shows a tighter margin between the two candidates. A New York TimesThe /Siena College poll of 656 likely voters from Oct. 5 to 8 showed Sheehy leading Tester, 52 percent to 44 percent. The margin of error was plus or minus 4 points.

State aggregate polls show Sheehy leading in the state as well, with FiveThirtyEight showing Sheehy up 5.3 percentage points as of Sunday at 49.6 percent over Tester at 44.3 percent. The Hill aggregate shows Sheehy at 51.4 percent compared to Tester’s 44.1 percent.

The Cook Political Report lists the race as “lean Republican.” The Hill estimates Sheehy has a 79 percent chance of swinging the state as of Sunday morning, while FiveThirtyEight’s forecast shows a 90 percent chance Sheehy will win the seat.