Rick Santorum won the Louisiana Republican presidential primary Saturday, beating front-runner Mitt Romney in the race to challenge President Obama. Jae C. Hong/AP hide caption

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A screen shot of President Obama from the trailer for his campaign's movie The Road We've Traveled. BarackObama.com/YouTube hide caption

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Peoria, Ill., as seen from across the Illinois River. Jeff Haynes/Reuters /Landov hide caption

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A supporter of Republican presidential candidate Mitt Romney holds a vintage campaign poster of Romney's father, George Romney, in Albion, Mich. Justin Sullivan/Getty Images hide caption

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Mitt Romney sings the national anthem before speaking at a Tea Party event at the Bakers of Milford Banquet Hall on Thursday in Milford, Mich. Scott Olson/Getty Images hide caption

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Mitt Romney shakes hands with supporters after a town hall meeting at Eagle Manufacturing in Shelby Township, Mich., on Tuesday. Andre J. Jackson/MCT/Landov hide caption

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Former Massachusetts Gov. and Republican presidential candidate Mitt Romney addresses supporters during a campaign rally at the Weber Paper Company Monday in Dubuque, Iowa. Chip Somodevilla/Getty Images hide caption

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Supporters seek autographs from Mitt Romney during a campaign event at the Family Table Restaurant Saturday in Le Mars, Iowa. Chip Somodevilla/Getty Images hide caption

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On Jan. 3, Iowans will caucus at 1,774 precincts across the state, in the first contest of the 2012 presidential nominating process. Above, Iowans caucus in 2004 at St. John's United Methodist Church in Des Moines, Precinct 87. Shaun Heasley/Getty Images hide caption

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Former Pennsylvania Sen. Rick Santorum speaks Tuesday at the Lincoln Cafe in Belle Plaine, Iowa. Among GOP candidates, Santorum had the state to himself on Tuesday. Chris Carlson/Associated Press hide caption

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Republican presidential candidates former Massachusetts Gov. Mitt Romney and former House Speaker Newt Gingrich squared off in the ABC debate in Des Moines, Iowa, Saturday night. Charlie Neibergall/AP hide caption

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Newt Gingrich, whose run for president nearly derailed earlier this year when many of his top staffers quit, now sits atop the polls. As a result, his campaign organization is growing. Here, he arrives at a town hall meeting last week in Staten Island, N.Y. Michael Nagle/Getty Images hide caption

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Republican presidential candidates Texas Gov. Rick Perry and former CEO of Godfather's Pizza Herman Cain talk after a forum sponsored by The Family Leader Saturday. Both men let their emotions show during the roundtable. Charlie Neibergall/AP hide caption

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