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

President Obama greets students after speaking at the University of Michigan in Ann Arbor on Jan 27. Young Republicans say they see an opportunity in 2012 to dent Obama's popularity among the youngest voters. Jewel Samad/AFP/Getty Images hide caption

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Jan White, left, Brenda Robertson, center, and Janet Freixas, right, count paper ballots at the headquarters of the Douglas County Republican Party Saturday in Minden, Nev., following county-wide Nevada caucus meetings. Ted S. Warren/AP hide caption

itoggle caption Ted S. Warren/AP