Frederick Westbrook, a retired Las Vegas hotel worker, voted for President Biden in 2020 — as a vote to get Donald J. Trump out of office. He now calls that “the biggest mistake of my life.”

“As a Black man in America, I felt he was doing unjust things,” he said of Mr. Trump. “He’s got a big mouth, he’s not a nice person.” None of that, in his view, has changed. But one thing has.

“Everything is just about the economy,” said Mr. Westbrook, who has started driving for Lyft to support himself on a fixed income in retirement. “I don’t really trust Donald Trump at all. I just think housing, food, my car, my insurance, every single piece of living has gone up.”

In a recent set of polls, Mr. Trump led Mr. Biden in five of six key battleground states, including Nevada. Across the states, Mr. Biden does not have the support of 14 percent of the respondents who said they voted for him in 2020 — voters like Mr. Westbrook who now say they will support Mr. Trump or a third-party candidate, or are undecided or won’t vote.

In follow-up interviews, many poll respondents were engaged on certain issues, and said those that Democrats are strongest on, like abortion rights and preserving democracy, were also important to them. They disliked Mr. Trump’s personality — a reason many voted against him in 2020 — and weren’t necessarily set on their vote.

But other issues had come to the fore and made them unhappy with how things were going — particularly inflation, immigration and foreign policy.