EPAepa03170362 A balloon man depicting Republican presidential candidate Rick Santorum is on display at an election night party in Mars, Pennsylvania, USA, 03 April 2012. Republican presidential primary elections were held today in Maryland, Washington D
dapdA hat with a campaign logo of Republican presidential candidate, former Massachusetts Gov. Mitt Romney is seen at a vendors table on the street in Harrisburg, Pa., Thursday, April 5, 2012. (Foto:Steven Senne/AP/dapd)
REUTERSREFILE - CORRECTING DATE Republican presidential candidate Mitt Romney addresses supporters during a "Repeal & Replace Obamacare" campaign in Metairie, Louisiana March 23, 2012. Louisianas primary will be held on Saturday March 24th. REUTERS/Sean G
REUTERSU.S. Republican presidential candidate Mitt Romney carries a baby after speaking to workers and supporters at a rally at Thompson Tractor in Birmingham, Alabama March 9, 2012. REUTERS/Marvin Gentry (UNITED STATES - Tags: POLITICS ELECTIONS)
dapdRepublican presidential candidate, former Mass. Gov. Mitt Romney pauses during a visit to St. Pauls Lutheran Church while campaigning in a Berlin, N.H. neighborhood, Thursday Dec. 22, 2011. (Foto:Charles Krupa/AP/dapd)
REUTERSSupporters of Republican U.S. presidential candidate Mitt Romney wave campaign signs at his "Super Tuesday" primary election night rally in Boston, Massachusetts, March 6, 2012. REUTERS/Jessica Rinaldi (UNITED STATES - Tags: POLITICS ELECTIONS)
ReutersREFILE - AMENDING RESTRICTIONS(L-R) Mitt Romney and his sons Tagg, Matt, and wife Ann are seen in this undated handout photo from the Romney for President campaign, received by Reuters February 3, 2012. REUTERS/Romney for President/Handout (UNITED
REUTERSU.S. Republican presidential candidate U.S. Rep. Ron Paul (R-TX) waves before the start of the Republican presidential candidates debate in Mesa, Arizona, in this February 22, 2012, file photo. Paul announced that he will no longer actively campaig