James Westcott, a Bronx resident who has been unemployed for two years, said he had been stopped by the police on three occasions. “One right after the other, by three different patrol cars,” Mr. Westcott, who is black, said. He also said the police had become less considerate, adding, “It started getting bad when Giuliani was mayor, and now it’s getting worse and worse.”

“You know it’s excessive when you see people get stopped who really don’t deserve to be stopped, like kids going to school,” Mr. Westcott, 44, said. “The police just jump out, stop them, search them, take their names down, then get back in their car and leave, and the kids don’t know what went on.”

But some New Yorkers, while conceding that the police show favoritism for one race over another, said the stop-and-frisk tactic’s ends justified the means.

“If that’s what it takes, I find it acceptable,” said Jani Kipness, 58, a special-education teacher from Brooklyn who is white. She said that she thought that officers “single out minority groups,” but that “if you look at the crime in New York, it’s less white people; that’s just the way it is.”

“I wouldn’t want to be stopped and frisked,” she added. “But if you look at cities like Detroit and other cities that have a way higher crime rate than New York, I think New York has to be doing something right.”

The stop-and-frisk practice has come under harsh criticism from civil liberties groups and some lower court judges. The issue has become a subject of debate among elected officials and has apparently captured the attention of the public: more than three-quarters of New Yorkers interviewed for the poll said they had heard a lot or some about it.

The criticism has prompted Mr. Kelly, who has argued strongly that the stop-and-frisk practice is an important crime-fighting tool, to pledge changes to ensure the lawfulness of the practice. The number of stops fell by more than 34 percent in April, May and June, compared with the previous quarter.