Republican presidential candidate Mitt Romney walks past Donald Trump's airplane as he arrives in Las Vegas on Tuesday, where he met with Trump for a fundraiser. Mary Altaffer/AP hide caption

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President Franklin D. Roosevelt and his Republican challenger, Kansas Gov. Alfred M. Landon (left), meet in September 1936. AP hide caption

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Rep.Thaddeus McCotter, R-Mich., is a regular on Twitter. Here, he plays guitar at a festival last July in Whitmore Lake, Mich. Bill Pugliano/Getty Images hide caption

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Mitt Romney greets the crowd during a campaign stop last week in St. Petersburg, Fla. Edward Linsmier/Getty Images hide caption

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Don Meikle attends an April job fair in Portland, Ore. A new poll shows the economy remains the most important factor for Americans in deciding who to back for president, but with adults split over who would best lead the U.S. economy. Rick Bowmer/AP hide caption

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Arkansas Senate President Paul Bookout, a Democrat, speaks in the Senate chamber at the Capitol in Little Rock on April 5. In November, Arkansans will vote for every seat in the state Legislature. Danny Johnston/AP hide caption

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