Republicans backing the Trump campaign have kept up their attacks on the military career of Gov. Tim Walz of Minnesota during the Democratic convention, accusing him, among other things, of having abandoned his fellow soldiers by retiring from the National Guard to run for Congress in 2006, months before his unit deployed to Iraq.

But the attack may not be having the intended effect. Several veterans, including undecided and conservative voters, said this week that they saw the sniping over Mr. Walz’s service as harmful to all veterans, in and out of the political arena.

The recent attacks on Mr. Walz, the Democratic nominee for vice president, were begun by his opponent on the Republican ticket, Senator JD Vance of Ohio, who served in the Marine Corps for four years. And they have been repeated by other prominent Republicans who are veterans, including 50 members of Congress who signed a letter this week claiming that Mr. Walz had lied and had “violated the trust” of other veterans.

“Name-calling, talking about people’s record, like, that’s not helpful,” said Vince Young, 32, a former Marine Corps mortarman and undecided voter who lives in Charlotte, N.C. He said his main concern was the economy, and that seeing one veteran disparaging another turned him off.

“I think it’s not really beneficial to anyone,” he said. “I want to hear, what are you going to do?”