President Obama shakes hands as he arrives at a rally Tuesday on the University of Wisconsin campus in Madison, Wis. Morry Gash/AP hide caption

itoggle caption Morry Gash/AP

Ken Buck accepts the Republican nomination for Senate on Aug. 10 in Loveland, Colo. Buck, the Weld County district attorney, defeated former Colorado Lt. Gov. Jane Norton in the primary. Eric Bellamy/The Daily Tribune/AP hide caption

itoggle caption Eric Bellamy/The Daily Tribune/AP

A new poll by Pew Research says that only 1 person in 3 knows President Obama is a Christian, while nearly 1 in 5 thinks he's a Muslim. Andrew Wardlow/AP hide caption

itoggle caption Andrew Wardlow/AP