So deep is the dislike for him in some quarters that people like Mrs. Cleveland’s husband, Doug, question the accuracy of polls that so consistently identify Mr. Trump as leading the field with around 32 percent. “I’ve never met a single one of them,” Mr. Cleveland said about those said to be backing Mr. Trump. “Where are all these Trump supporters? Everyone we know is supporting somebody else.”

These are the lamentations of the 68 Percent — the significant majority of Republican voters here who are immune to Mr. Trump’s charms and entreaties, according to a battery of voter interviews on Thursday at campaign events for his rivals…

“I understand people say, ‘I’m sick of this political correctness.’ I get that,” she said. “But there’s also an argument for some measure of civility. I mean, he’s just not somebody who you can say, ‘I’m proud he’s our president.’”

Several voters insisted they had tried hard to close their eyes and picture Mr. Trump as the leader of the free world. They could not do it, they say.

“He’ll lose his cool when he gets up with Putin or one of those, and tell them to go fly a kite,” predicted Kathy DeFreitas, who lingered at a pizza parlor in Manchester after listening to Senator Ted Cruz of Texas.