Republican presidential candidate, former Pennsylvania Sen. Rick Santorum waves as he visits the campaign headquarters in Brookfield, Wis., Saturday, March 31, 2012. (AP Photo/Jae C. Hong)

Associated Press
Republican presidential candidate, former Pennsylvania Sen. Rick Santorum waves as he visits the campaign headquarters in Brookfield, Wis., Saturday, March 31, 2012. (AP Photo/Jae C. Hong)
Republican presidential candidate, former Pennsylvania Sen. Rick Santorum waves as he visits the campaign headquarters in Brookfield, Wis., Saturday, March 31, 2012. (AP Photo/Jae C. Hong)