Obama is surrounded by former presidents in the Oval Office in 2009. Two of his predecessors — George W. Bush and Bill Clinton — won two terms, while two others — George H.W. Bush and Jimmy Carter — left office after just one.

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Senate Majority Leader Harry Reid of Nevada (center), accompanied by Sen. Charles Schumer, D-N.Y. (left), tells reporters that he is moving ahead with a Democratic plan to trim the deficit and avert a debilitating default on Friday. J. Scott Applewhite/AP hide caption

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Former Alaska Gov. Sarah Palin stands near her tour bus outside a hotel in Boston on June 2. Steven Senne/AP hide caption

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At a 1993 demonstration in New York, gay rights advocates voiced their opposition to the military policy that became "don't ask, don't tell." Porter Gifford/Getty Images hide caption

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