Tim Sheehy Faces Scrutiny Over Military Records as He Continues Leading the Polls in Montana's Senate Race

Montana Senate GOP candidate Tim Sheehy, who has partly focused his campaign on his record as a Navy SEAL, is facing heavy scrutiny after records showed he was not discharged from the military for medical reasons, as he has previously said. Sheehy is favored to win the race for Montana's seat, the most vulnerable seat for Democrats ahead of Election Day.

Throughout his career, Sheehy said his time in the military was cut short due to a health issue he developed, but it wasn't the reason for which he ultimately left.

In the book "Mudslingers: A True Story of Aerial Firefighting," Sheehy wrote that he suffered a bad case of decompression sickness, commonly known as the bends, while he was riding in a mini-submarine during a training exercise in Hawaii, causing "a tiny hole in my heart."

"There would be a period of recovery and evaluation, I was told, before I could return to active duty," he wrote.

He ultimately decided to resign instead. "If I couldn't be out in the field, leading from the front, then it was time to consider doing something else," adds another passage of the book. "I had put in my time; I was free to go if that was what I wanted."

However, a heavily-redacted two-page document obtained by NBC News indicates that Sheehy voluntarily resigned his commission and does not list any medical condition that forced him out of service.

The revelations add to the number of statements he has made about his tenure in the military that have come into question. He was already facing scrutiny for his claim that he was shot in Afghanistan, which has been contradicted by a National Park Service ranger who has told reporters that Sheehy shot himself in an accident at Glacier National Park in 2015.

In interviews with conservative podcast hosts, Sheehy has also said he was forced out of the military because of injury.

"So finally, they said, 'Hey, you're at the end of the road, you know, you've got shrapnel in you, you've got a bullet in you, you've had a head injury, you know, you're out of here,'" Sheehy said on the "First Class Fatherhood" podcast in November.

Democratic Sen. Jon Tester, who holds the most vulnerable seat for the party in the Senate, and his allies say the changing stories should diminish voter trust in Sheehy.

"He has done things that, in a previous cycle, would have been disqualifying on their own," Tester said after a rally for Democratic candidates in Havre in the state's Hi-Line region along the Canadian border. "But we're in a different time now and we'll see. I still think Montanans are going to react to this in a way that won't be good for him."

But despite scrutiny, Sheehy is still comfortably leading in the polls, as he is favored to win the race for The Treasure State.

A recent poll by Emerson College conducted between Oct. 23-25 showed Sheehy holding 51% support and Tester at 48%. Likewise, a polling average by Decision Desk HQ and The Hill showed Sheehy leading Tester by 4.8 percentage points, at 50% to Tester's 45.2%. The Cook Political Report also rates this race as leaning Republican.