Former Rep. Kerry Bentivolio, running for his old seat in Michigan’s 11th District, is suing one of his fellow GOP primary challengers for $10 million for allegedly defaming his military record by questioning its authenticity.

Bentivolio and his lawyer are claiming that Rocky Raczkowski — another Republican in the crowded primary field for what could be one of the nation’s most hotly contested House races in November — has a history of waging a “malicious defamation campaign … telling multiple third parties that Bentivolio’s military record is fraudulent and fake,” the Detroit Free Press reported.

Bentivolio enlisted in the Army in 1968 and was deployed to Vietnam as an infantry rifleman in 1970, earning a handful of medals and awards during his service, including the Vietnam Service Medal and the Bronze Star.

Raczkowski, a retired lieutenant colonel in the Army Reserve and former Michigan state representative, has denied the claims in the lawsuit.

But he has publicly questioned comments Bentivolio made to him in private about his service, Raczkowski told the Free Press.

In 2012, Raczkowski said, Bentivolio told him he had received a Silver Star, two Bronze Stars and three Purple Hearts for his service. “I questioned that,” Raczkowski told the Free Press.

Bentivolio’s legal team doubled down on the allegations, though.

“Rocky is a liar,” Bentivolio’s lawyer, Debbie Schlussel, said.

It is difficult for political candidates to win lawsuits against their opponents because comments made about about people running for office fall under the umbrella of protected political speech. Bentivolio’s team, however, has said Raczkowski’s public comments were “not privileged, not opinion, not truthful and wholly unjustified.”

The men are two of at least seven Republicans vying for the party nomination in the August 7 primary. GOP Rep. Dave Trott, who defeated then-incumbent Bentivolio in the 2014 primary, is retiring at the end of this term.

At least six Democrats have also filed papers to run for the seat, which political handicappers expect could go either way in November.

President Donald Trump carried the 11th District by 4 points in the 2016 election.

Inside Elections with Nathan L. Gonzales rates the race a Tossup.