PHOTO OF THE DAY: Republican presidential candidate and former Pennsylvania Sen. Rick Santorum arrives at the USS Yorktown in Mount Pleasant, S.C., on Tuesday. (PHOTO: Matt Rourke/AP)

This photo is both cool and meta. (PHOTO: Liz Lynch)

“He is a very persistent soul, as people have found out in Iowa,” said Barry Lynn, a critic who heads the group Americans United for Separation of Church and State. “He takes positions that are very stark, easy to understand … and he doesn’t give up. He simply doesn’t go away.”

Sanctimonious or Sincere? Santorum Evoked Strong Feelings in Congress

PHOTO OF THE DAY: Republican presidential candidate and former Pennsylvania Sen. Rick Santorum waits to be introduced at a campaign stop at Valley High School in West Des Moines, Iowa, on Tuesday. (PHOTO: Charlie Riedel/AP)