Representative Jason Crow, Democrat of Colorado, pressed Defense Secretary Pete Hegseth in a letter released on Thursday to clarify his earlier statements about whether his personal lawyer influenced key military promotions.

During a hearing in April, Mr. Crow asked whether Timothy Parlatore, a lawyer who has represented Mr. Hegseth and President Trump, was working on behalf of senior military officers being considered for promotions by Mr. Hegseth.

Mr. Hegseth said that Mr. Parlatore, who is also his “special adviser” at the Pentagon and a Navy reservist, had no role in choosing senior military leaders.

“He doesn’t represent anyone,” Mr. Hegseth testified before the House Armed Services Committee. “He’s a legal adviser and always has been.”

Last month, The New York Times reported that Adm. Daryl Caudle, when he was under consideration to be the chief of naval operations, had hired Mr. Parlatore to help him resolve comments he had made to sailors about the Pentagon’s Sexual Assault Prevention and Response program, officials said. Some interpreted Admiral Caudle’s remarks as blaming victims.

Mr. Crow asked Mr. Hegseth in the letter to explain the apparent contradiction between his congressional testimony and the Times report.

“Our military leaders make decisions of life and death nearly every day, and the American people must see that those leaders are chosen with integrity, merit and their safety top of mind,” Mr. Crow said in a statement. “Undermining this process puts our national security at risk. Hegseth must set the record straight before the American people.”

In an interview with The Times on Wednesday, Mr. Parlatore called Mr. Crow’s letter “misguided.”

“The record is clear that Admiral Caudle had already been selected before he and I had ever spoken,” Mr. Parlatore said. “All of the secretary’s answers at the hearing were completely and totally truthful.”

As part of his work for Admiral Caudle, Mr. Parlatore suggested possible witnesses and accompanied the Naval officer to his interview with investigators.

After the inspector general found the allegations of wrongdoing by Admiral Caudle to be unsubstantiated, his nomination was sent to Mr. Trump for approval.

The Pentagon declined to comment on Mr. Crow’s letter.

In an earlier statement, Sean Parnell, the chief Pentagon spokesman, said that all promotion decisions in the Pentagon were based “strictly on merit,” and added that Mr. Parlatore was “in full compliance with all ethics laws and regulations.”

Mr. Hegseth selected Admiral Caudle for the job leading the Navy even though he was not on a list of candidates recommended by senior Navy officials for the position. He took over as the 34th chief of naval operations last summer.

“It appears that Mr. Parlatore’s involvement extended well beyond that of a special adviser and into matters traditionally reserved for department leadership and established military personnel processes,” Mr. Crow wrote in the letter to Mr. Hegseth.

Mr. Parlatore’s involvement in promotion decisions raises “significant questions about potential conflicts of interest, adherence to federal ethics standards, and the integrity and impartiality of the military’s promotion system,” Mr. Crow continued.

He asked Mr. Hegseth to provide a written response clarifying his testimony by Sept. 10.