MIDWEST CITY, Okla. — Representative Tom Cole started hearing it in the morning when he went to grab coffee.

“I was just at Starbucks, and a woman there recognized me,” he told a Chamber of Commerce gathering here. “She said, ‘Everybody here’s a no on Syria.’ ”

Mr. Cole, a six-term Republican, would seem a potential candidate to support President Obama on Syria. A pragmatic Congressional veteran, he has been open to compromise with the White House in the past and is not afraid to break with House conservatives. But after portraying himself as leaning against a strike, Mr. Cole on Thursday afternoon came down firmly in the opposition when his office issued a statement announcing that he would vote no.

Given the intensity of opposition in his district, he said it would take a “road to Damascus experience” to change his mind now. “I literally cannot walk across the parking lot without being stopped to talk about this issue,” he said. “I haven’t seen anything quite like this.”