TACOMA, Wash. — It was predictable that Rick Santorum — or any Republican presidential candidate — would be met with protests here Monday night as he spoke outdoors, down the street from an Occupy encampment and near the entrance to a public university.

Shortly after the former senator from Pennsylvania began addressing a receptive crowd, a group of young protesters in the front row began chanting slogans such as “go away” and “right-wing bigot,” a reference to Mr. Santorum’s opposition to gay marriage, one of them said afterward. The surging GOP-candidate then spent the next hour battling the vocal minority.