谁为奥巴马赢得了大选？

http://www.csmonitor.com/USA/DC-Decoder/Decoder-Wire/2012/1107/Election-results-2012-Who-won-it-for-Obama-video

Exit polls find that a key to Obama's victory was winning

93 percent of African-Americans,

71 percent of Hispanics,

73 percent of Asians.

Mitt Romney took most of the white vote, which is 72 percent of the electorate. But it wasn't enough.