Romney seeks knockout blow against Santorum

Presidential candidate Rick Santorum, with wife Karen, shows off a cheese-head hat at Simon's Specialty Cheese in Appleton, Wis., on Monday. (Associated Press)

Presidential candidate Rick Santorum, with wife Karen, shows off a cheese-head hat at Simon's Specialty Cheese in Appleton, Wis., on Monday. (Associated Press)

More Photo Galleries

Happening Now