In that interview, Peach described how Sheehy's gun accidentally went off while he was in his car, resulting in a bullet being lodged in his arm. The park ranger found a shell casing after inspecting the Montana businessman's gun, and wrote up a $525 citation for discharging a firearm inside a national park.

"I remember Sheehy obviously being embarrassed by the situation but at the same time thankful that it wasn’t worse," Peach said.

A spokesperson for Sheehy's campaign dismissed Peach's claims, accusing the ranger of attempting to spread a "defamatory story." The Republican Senate candidate's explanation for the 2015 citation was that he lied to Peach about injuring himself in order to cover up the fact that he was wounded by friendly fire while serving in Afghanistan. But Peach insisted his own recollection was accurate.

"[Sheehy] said that questioning his military service was ‘disgusting’,” Peach told the Post. “What is disgusting is saying a wound from a negligent, accidental firearm discharge is a wound received in combat.”

This isn't the first time Sheehy has been accused of lying about his background. While he has sold himself to Montana voters as an authentic rural American, he actually grew up in a multimillion-dollar lake house in Minnesota which the Daily Beast reported was "three miles from a Trader Joe's market." And while Sheehy said he and his wife scrimped and saved to launch his aerial firefighting business, the Beast reported that he was actually buoyed by a six-figure investment from his parents.

Sheehy is currently favored to defeat Tester in Montana's Senate race, with FiveThirtyEight's aggregated polling data showing him with a lead of anywhere from six to eight percentage points. However, Tester has maintained a significant financial advantage throughout the race. His $7.4 million in cash on hand — which dwarfs Sheehy's $4 million — could be a deciding factor in turning out voters between now and November 5.