Texas Rep. Ron Paul (right) talks with the his presidential campaign manager, Jesse Benton, backstage at the Republican Party's Iowa straw poll last August. Charles Dharapak/AP hide caption

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Ten states hold GOP nominating contests on March 6. Here a voter heads to a polling station Tuesday morning in Cambridge, Mass., where former Gov. Mitt Romney is expected to win his home state. Emmanuel Dunand /AFP/Getty Images hide caption

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Former Massachusetts Gov. Mitt Romney waves to the crowd as he is introduced at the start of Wednesday night's Republican presidential debate in Mesa, Ariz. Ross D. Franklin/AP hide caption

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Republican presidential hopeful and former U.S. Sen. Rick Santorum speaks to supporters, flanked by his daughter, Elizabeth (left), and wife, Karen. Whitney Curtis/Getty Images hide caption

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