Iowa caucusgoers deposit their ballots on Jan. 3 at a school in Des Moines. On Thursday, the state GOP said it could not account for all votes from the caucuses. Jewel Samad /Getty Images hide caption

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Republican presidential candidates Rick Santorum (left) and Mitt Romney during a debate in South Carolina on Monday. Charles Dharapa/pool/Getty Images hide caption

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Barb Hansen tallies votes during a GOP caucus in precinct 42 near Smithland, Iowa, on Tuesday, Jan. 3, 2012. Dave Weaver/AP hide caption

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A volunteer works the phones Tuesday at Newt Gingrich's New Hampshire campaign headquarters in Manchester. Alex Wong/Getty Images hide caption

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Gingrich with one of the many pieces of farm equipment he encountered on a last-minute campaign swing through Iowa. This tractor was on display at the Heartland Acres Agribition Center on Monday in Independence, Iowa. Andrew Burton/Getty Images hide caption

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A supporter of Texas governor Rick Perry places campaign signs outside the Hotel Pattee before an event on Monday in Perry, Iowa. Andrew Burton/Getty Images hide caption

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