ARDEN HILLS, Minn.—Waiting for Rep. Ron Paul to speak at Bethel University on Saturday night, Tom Dippel said it was the idea of returning to the gold standard that drew him to the Texas Republican.

"My main issue is really economics, the currency primarily. We have to get back to sound money," said Mr. Dippel, who organizes for Mr. Paul along the Minnesota-Wisconsin border.

Mr....