** FILE ** Former Pennsylvania Sen. Rick Santorum campaigns for the Republican presidential nomination at Bob's Diner in Carnegie, Pa., on Wednesday, April 4, 2012. (AP Photo/Jae C. Hong)

Photo by: Jae C. Hong

** FILE ** Former Pennsylvania Sen. Rick Santorum campaigns for the Republican presidential nomination at Bob's Diner in Carnegie, Pa., on Wednesday, April 4, 2012. (AP Photo/Jae C. Hong)