Mr. Fullerton, who usually votes for Democrats, said business had slowed since last year. His company imports many of its parts, he said, and it has had to raise prices to cover the cost of tariffs, in some cases by as much as 15 percent. He said that he did not yet see evidence of a recession, but that he was watching warily.

“I would think twice about doing any major home renovation or anything, probably,” he said. “It enters your mind, whereas last year it wouldn’t really have entered your mind.”

Sign up for On Politics to get the latest election and politics news and insights. Sign up for our politics newsletter

Mr. Kugler’s company has also been affected by tariffs. But he said that business over all remained strong, and that the local economy had improved since Mr. Trump took office. And Mr. Kugler, a conservative Republican, said Mr. Trump’s trade policies were worth any short-term cost.

“It’s hard sometimes, but for the long haul I think it’s the right thing to do,” he said. “What China’s doing to us is just outright criminal.”

Mr. Kugler said the economy was the most important issue to him, and said he would consider rethinking his support for Mr. Trump if conditions soured — he just doesn’t expect that to happen. Mr. Fullerton, too, said he tried to evaluate evidence objectively, though he acknowledged that his political views probably affected his interpretation.

“I’m sure I’m human, and I probably don’t always see both sides of everything,” Mr. Fullerton said. “I think I’m guilty of it. But I try to be aware of it.”

The partisan divide in consumer confidence is a relatively new phenomenon. In the early 1980s, Democrats and Republicans largely saw eye to eye on the state of the economy, according to the University of Michigan’s long-running survey of consumer sentiment. By the 2000s, a gap had emerged, with partisans tending to view the economy more positively when their preferred party was in power. The gulf has only widened since.