Republican Navy SEAL veteran Tim Sheehy defeated Democratic Senate Veterans Affairs Committee Chairman Jon Tester in Tuesday's Senate race in Montana.

Sheehy's victory over the three-term incumbent will give Republicans a majority in the Senate in the next session of Congress and could upend military and veterans policy going forward, with the departure of one of the upper chamber's most prominent Democratic voices on those issues.

“I have served our country since I was 18 because when your country calls, you must answer, and I am incredibly honored by your support and the trust you have placed in me to fight for you and Montana as your neighbor “U.S. Senator,” Sheehy posted on social media Wednesday, hours after The Associated Press called the race for him.

Read more: Trump won. Here's what that could mean for the military.

Because Tester was a leading voice on veterans policy in the Senate and Sheehy was a veteran himself, veterans issues played a key role in their campaigns as both candidates looked for an edge in a race that was seen as crucial in determining which party wins the Senate next year would control.

According to U.S. Census Bureau data, Montana has the third-highest veteran population per capita in the country, at 9% of the state's adults. According to the AP, Sheehy won by about 8.6%, with 93% of the vote counted as of Wednesday afternoon.

Sheehy's campaign materials contained strong references to his being a SEAL, and he regularly mentioned his military service in campaign ads and speeches.

But aspects of his military career were also questioned during the campaign, particularly his account of being shot in the arm in Afghanistan.

While Sheehy said in campaign speeches and in his memoirs that he was shot in Afghanistan, the Washington Post revealed earlier this year that he told a National Park Service ranger in 2015 that he accidentally shot himself while his gun was at Glacier National Park fell on the ground during a visit to Afghanistan.

According to the Post's reporting, Sheehy claimed he injured himself in a fall and lied to the park ranger when the old gunshot wound was discovered because the shooting in Afghanistan was a friendly attack by a fellow SEAL and he was worried , disclosing this, which could lead to a military investigation, even though he had already retired from active service at the time.

As Tuesday's election approached and Sheehy was ahead in the polls, the park ranger and a SEAL with whom Sheehy served came forward and disputed Sheehy's on-the-record account. When pressed in an interview over the weekend about the inconsistencies in his story, Sheehy said there was no medical documentation to support his account of being shot in Afghanistan and also suggested it was an Afghan ally who shot him, not a fellow SEAL.

Meanwhile, throughout the campaign, Tester touted his accomplishments as chairman of the Senate Veterans Affairs Committee, including his support in enacting sweeping pollution legislation known as the PACT Act.

In addition to leading the Veterans Affairs Committee, Tester has served as chairman of the Senate Appropriations Committee's Defense Committee for the past three years. In that position, he was a strong supporter of increasing the Pentagon budget beyond the demands of the Biden administration.

But Tester's experience in veterans and military affairs and his personal image as a moderate were not enough to save his seat in a red wave that also saw former President Donald Trump return to the presidency.

“Look, I’m very, very blessed,” Tester said after his loss, according to the AP. “I had a great 18 years in the U.S. Senate. I’ve met some incredible people along the way and had the opportunity to do some great things to move this state and country forward.”

Related: The SEAL vs. the Chairman: Why veterans issues matter in Montana's Senate race

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