President Obama answers questions during his news conference at the White House on Tuesday. Pablo Martinez Monsivais/AP hide caption

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Police stand guard in front of the U.S. Supreme Court on Wednesday as the justices hear arguments on the constitutionality of the federal Defense of Marriage Act. Jewel Samad/AFP/Getty Images hide caption

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Republican presidential nominee Mitt Romney pauses while speaking at a campaign rally at the Patriot Center at George Mason University in Fairfax, Va., on Monday. Charles Dharapak/AP hide caption

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A new NPR poll shows the outcome of the Nov. 6 election is too close to call. Mitt Romney leads President Obama nationwide; Obama leads Romney in key battleground states. Both leads are within the poll'€™s margin of error. Pablo Martinez Monsivais/AP hide caption

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Mitt Romney shakes hands with President Obama after their final debate Monday in Boca Raton, Fla. Eric Gay/AP hide caption

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Democratic presidential candidate George McGovern talks about the bombs being used in Vietnam at a $250-a-person fundraising dinner in Los Angeles on Sept. 27, 1972. AP hide caption

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President Obama and former Massachusetts Gov. Mitt Romney participate in the second presidential debate at Hofstra University in Hempstead, N.Y., on Tuesday. Charles Dharapak/AP hide caption

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