FOUNTAIN HILLS, Ariz. — David Rau wasn’t sure about Donald Trump. So the landscape contractor strolled over to the main park in this Phoenix suburb to watch one of the businessman’s recent rallies and decide for himself.

Demonstrators pulled their cars across an access road to block people driving to the event. Dozens marched to the park and stood by Rau, chanting “Stop the hate!” as he tried to listen. He left a Trump convert. “I’ve got the right to listen to somebody speak, don’t I?” Rau asked.

Trump’s rise in the Republican presidential contest has sparked increasingly confrontational protests, mobilized his opponents and drawn scrutiny of the GOP front-runner’s rhetoric and the sometimes rough way his campaign handles dissent. But as demonstrators escalate their tactics, they also risk helping Trump, especially among Republican voters his rivals are furiously trying to persuade to reject the billionaire businessman.

“I encourage people to speak out against Trump in a forceful but respectful manner because some of these protests are only serving to help him,” said Tim Miller, a spokesman for a Republican group trying to stop Trump.