Former President Donald J. Trump cast his ballot for himself in Palm Beach, Fla., on Tuesday and said this was likely to be his last campaign, no matter the outcome.

Mr. Trump arrived with his wife, Melania, from his private club and residence, Mar-a-Lago. Pressed by reporters on whether he might concede if he lost, he said, “If I lose an election, if it’s a fair election, I’m going to be the first one to acknowledge it, and I think it’s — well, so far, I think it’s been fair.”

But he also raised concerns about voting machines and the length of time it takes to count ballots, two things he made central to his lies about a stolen 2020 election. He has not explained what conditions he might require to deem an election fair, even as he has told supporters that he believes the only way Democrats can win is by cheating.

Mr. Trump, who has at times criticized his advisers during rally speeches, said he was confident in his team and thought it had run his campaign well. “But in order to make that stick, you have to win,” he said.

He said there should be no violence after the election, despite his own violent rhetoric during the campaign and vows of retribution against his enemies.

“My supporters are not violent people,” he said, not addressing the actions of a mob of his supporters who stormed the Capitol on Jan. 6, 2021, because they were unhappy with his election loss. “I don’t have to tell them that.”

He told reporters he was “very honored” to find out the voter lines were long. Asked if he expected this would be his last campaign, Trump said, “Yeah, I would think so.”

Mr. Trump would not answer how he voted on a Florida ballot measure about abortion rights. Polls have shown that reproductive rights are a top issue for female voters and that Trump is facing a deficit with women. But when a female reporter pressed him on the issue, he told her she should “stop talking about that.”

The small recreation center turned polling station was somewhat chaotic as the Trumps arrived. Helicopters hovered overhead, and Trump supporters wore T-shirts with the former president’s mug shot.