Montana Republican Matt Rosendale is quitting Congress over "death threats" following the publication of "false and defamatory" rumors about an affair. 

The dramatic decision comes about a month after Rosendale suspended a short-lived Senate campaign.

The congressman's wife and family defended him from the affair allegations, which were shared initially by former Democratic senator Heidi Heitkamp.

Montana Republican quits Congress

Elected in 2020, Rosendale became known as a vocal Trump supporter, and his controversial flair put him at odds with party leadership.

Rosendale's Senate bid was opposed by the party's campaign arm, which embraced former Navy SEAL Tim Sheehy.

Incumbent Democrat Jon Tester (D), who defeated Rosendale in 2018, is considered one of the most vulnerable Democratic senators this cycle, and Republican leaders thought Rosendale would be a risky candidate.

After President Trump endorsed Sheehy, Rosendale dropped his campaign, which had lasted about a week.

Rosendale then announced he would seek re-election, entering a crowded Republican primary for his House seat.

His campaign threatened to take legal action against Heidi Heitkamp after she spread rumors on a podcast about Rosendale impregnating a 20-year-old staffer.

Rosendale's wife Jean dismissed the allegation as "political mudslinging at its worst."

"False and defamatory"

In a statement, Rosendale said he would not seek re-election over threats that had "taken a serious toll" on his family.

"I have been forced to have law enforcement visit my children because of a death threat against me and false and defamatory rumors against my family," Rosendale said in a statement.

"This has taken a serious toll on me, and my family," he went on. "It has caused a serious disruption to the election of the next representative for MT-02."

"In the best interest of my family and the community, I am withdrawing from the House race and will not be seeking office," he added.

Crowded primary

Rosendale was elected in 2020 to represent Montana's sole, at-large congressional district.

After the 2020 census, Montana gained another district for the first time in decades and Rosendale won re-election by a landslide in the 2nd district.

Known for rocking the boat, Rosendale was often described in the media as a member of the "far-right" and he was one of eight Republicans who voted to oust former Speaker Kevin McCarthy (R-Ca.) last year.

With Rosendale out, candidates from both parties are lining up for his seat. The district favors Republicans heavily, leaving Democrats with a tall hill to climb.

Some of the Republican contenders include U.S. Rep. Denny Rehberg, Montana state Auditor Troy Downing and Superintendent of Public Instruction Elsie Arntzen.