Aaron Dimmock, a retired Navy officer and aviator, has entered the Republican primary to challenge Representative Matt Gaetz of Florida — jumping into the race hours before a filing deadline last Friday.

Mr. Dimmock’s campaign committee shares a treasurer with American Patriots PAC, a group that was used by former Speaker Kevin McCarthy to support candidates who were aligned with him in the 2022 midterms. Mr. Gaetz led the revolt among House Republicans that ultimately ousted Mr. McCarthy from the speakership.

Mr. Dimmock and representatives of American Patriots PAC did not respond to requests for comment. The primary for the First Congressional District, which covers Pensacola and the western Florida Panhandle, will take place on Aug. 20.

Mr. Dimmock, a graduate of the United States Naval Academy, served as a pilot for the P-3 surveillance plane for the Navy. In an interview with the U.S. Naval Academy Alumni Association in 2020, Mr. Dimmock said that he had deployed to Bosnia and Kosovo and had completed several tours in the Middle East. He also described flying surveillance missions over New York City in the immediate aftermath of the Sept. 11, 2001, attacks on the World Trade Center. He became an instructor pilot, later worked as a recruiting officer and closed out his career as a Navy liaison in the Pentagon. The Navy operates a major air base in Pensacola.

Mr. Gaetz quickly attacked Mr. Dimmock on social media, pointing to LinkedIn posts that Mr. Dimmock made as a business consultant in 2020 in support of racial diversity and the Black Lives Matter movement after the murder of George Floyd by the Minneapolis police officer Derek Chauvin.

“Meet Aaron W. Dimmock,” Mr. Gaetz wrote. “The B.L.M. supporting D.E.I. instructor running against me in the Republican Primary. I knew former Representative McCarthy would be getting a puppet of his to run. I didn’t know it would be a Woke Toby Flenderson!”