Former Speaker Kevin McCarthy (R-Calif.) said in an interview published Wednesday that he is backing a primary challenger to Rep. Matt Gaetz (R-Fla.) — marking the latest development in their high-profile feud.

McCarthy told Politico he is he is backing former naval aviator Aaron Dimmock in the primary. In the interview, the former Speaker also ramped up his criticisms of his long-time rival, who is the subject of an ongoing House Ethics Committee investigation.

“Gaetz is the Hunter Biden of the Republican Party,” McCarthy said. “He’s got an opponent who is pro-life, pro-Second Amendment, trained at Pensacola, went to the Naval Academy and flew jets to defend us while Gaetz was getting kicked out of high school, buying coke and paying minors for sex.”

McCarthy was seemingly referring to an ongoing probe into allegations that Gaetz engaged in sexual misconduct with minors and illegal drug use. The Department of Justice declined to prosecute Gaetz on sex trafficking allegations last year.

Gaetz responded to McCarthy’s backing of Dimmock with a post on the social platform X, calling Dimmock “Missouri-Based” and quoting a Politico article saying he had “voiced support for diversity and the Black Lives Matter movement following the murder of George Floyd.”

“Who thinks Kev and DEI Dimmock should campaign together in Northwest Florida? I sure do!” Gaetz wrote in the post.

In a statement to The Hill, Gaetz said he wouldn’t take “behavior advice” from McCarthy, pointing to unsubstantiated rumors the former Speaker had an affair with another House member.

Dimmock filed to run as a Republican in Gaetz’s district last month for the Aug. 20 primary, making him the only challenger to the incumbent. Gaetz’s campaign quickly responded by resurfacing apparent social media posts by Dimmock and labeling him as a “DEI Enthusiast.”

A campaign committee, Friends of Matt Gaetz, launched a website that labels Dimmock as “woke” and as a supporter of diversity initiatives. It also includes links to donate to Gaetz’s campaign.

McCarthy and Gaetz have been locked in a feud for months, especially after Gaetz led the effort to oust McCarthy from the Speakership last fall. The California Republican has repeatedly said that the ethics investigation was one of the reasons Gaetz decided to lead the effort to remove him last fall.

Gaetz has maintained that his effort to boot McCarthy was not personal.

The Hill has reached out to Dimmock’s campaign for comment.