Former House Speaker Newt Gingrich. Win McNamee/Getty Images hide caption

itoggle caption Win McNamee/Getty Images

Republican presidential candidate and former Massachusetts Gov. Mitt Romney at his victory party Tuesday in Schaumburg, Ill. Chip Somodevilla/Getty Images hide caption

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Republican presidential candidate Rick Santorum with supporters Tuesday night in Lafayette, La. Louisiana's primary is on March 24. Sean Gardner/Getty Images hide caption

itoggle caption Sean Gardner/Getty Images