President Obama has "often confounded his opponents by defying political stereotypes," says Julian Zelizer, a presidential historian at Princeton University. Saul Loeb/AFP/Getty Images hide caption

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The USS Barry launches a Tomahawk cruise missile Saturday in support of Operation Odyssey Dawn. The operation targeted radar and anti-aircraft sites along Libya's Mediterranean coast. U.S. Navy/Getty Images hide caption

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A microphone is ready for broadcast on Election Day in November 2010 at NPR headquarters in Washington, D.C. Alyson Hurt (alykat)/Flickr hide caption

itoggle caption Alyson Hurt (alykat)/Flickr