When the Tea Party uprising gathered force last spring, Mr. Stewart saw painfully familiar cultural and rhetorical overtones. Mr. Stewart viewed the questions about Mr. Obama’s birthplace as a proxy for racism, and he was bothered by the “common message of intolerance for the opposition.”

“It’s either you’re with us or you’re the enemy,” he said.

Mr. Stewart heard similar concerns from other civil rights activists around the country. They could not help but wonder why the explosion of conservative anger coincided with a series of violent acts by right wing extremists. In the Inland Northwest there had been a puzzling return of racist rhetoric and violence.

Mr. Stewart said it would be unfair to attribute any of these incidents to the Tea Party movement. “We don’t have any evidence they are connected,” he said.

Still, he sees troubling parallels. Branding Mr. Obama a tyrant, Mr. Stewart said, constructs a logic that could be used to rationalize violence. “When people start wearing guns to rallies, what’s the next thing that happens?” Mr. Stewart asked.