7 / 20

Republican presidential candidate, former Pennsylvania Sen. Rick Santorum greets supporters at an election night party in Cranberry Township, Pa., Tuesday, April 3, 2012. (AP Photo/Gene J. Puskar)

Republican presidential candidate, former Pennsylvania Sen. Rick Santorum greets supporters at an election night party in Cranberry Township, Pa., Tuesday, April 3, 2012. (AP Photo/Gene J. Puskar)

Rick Santorum concedes

Rick Santorum called Mitt Romney Apr. 10 to say he is ending his presidential campaign, Yahoo News has learned.