Defense Secretary Pete Hegseth on Monday spoke at a campaign event boosting the President Donald Trump-backed challenger to Rep. Thomas Massie, R-Ky., ahead of Kentucky’s primary elections on Tuesday.

“I’m proud here to stand with Ed Gallrein, because he led warriors in combat,” Hegseth said at an event in Hebron, Kentucky. “He led at the very highest levels of special operations. He served with distinction as a Navy SEAL, rose into leadership within the elite ranks of SEAL Team Six, one of the most demanding combat organizations on planet earth.”

The event was hosted by the nonprofit organization America First Works, a pro-Trump group. Gallrein, who entered the race after Trump’s urging, spoke shortly before Hegseth.

In his remarks, Gallrein said service members “deserve a commander-in-chief who has their back and leaders they can trust. They have them in Donald Trump, and they have them in Pete Hegseth, don’t they?”

The New York Times was first to report that Hegseth would attend the event.

It’s highly unusual for the defense secretary to participate in a political event. Massie, a vocal Trump critic who led the campaign for the release of government records on Jeffrey Epstein, was first elected to Congress in 2012. Massie has also opposed Trump and Hegseth’s handling of the Iran war.

Hegseth nodded to the atypical nature of his appearance in his remarks, saying, “I have to say up front, for the lawyers, that I’m here in my personal capacity as a private citizen, a fellow American, and a fellow combat veteran.”

Guidelines for Defense Department employees and service members say that they should be “mindful of the various limitations that exist when it comes to participation in political activity, particularly during an election year.”

Before the event, Pentagon spokesman Sean Parnell told NBC News in a statement that Hegseth would appear only “in his personal capacity.”

“No taxpayer dollars will be used to facilitate his visit,” Parnell said in a statement. “His participation has been thoroughly vetted and cleared by lawyers, including the Department of War Office of General Counsel, and does not violate the Hatch Act or any other applicable federal statute.”

In an interview on Fox News Monday, Gallrein accused Massie of betraying conservative values by blocking the president’s agenda and aligning himself with “radical Democrats.” Gallrein also denounced Massie for being a “Never Trumper” who only rejoined the Republican Party after Trump’s re-election loss.

Massie’s campaign didn’t respond to a request for comment.