How did Barack Obama win the presidential election in 2008? Was it A.) He had better ideas? B.) The nation was ready for change? Or C.) John McCain/Sarah Palin were so ridiculously unqualified that a hot ham sandwich could have beaten them? The answer is all of the above, with one additional caveat. The real reason for Obama’s victory in 2008 was the vastly more organized and enthusiastic ground game he had compared to McCain.
http://drjasonjohnson.com/2011/09/16/how-president-obama-can-win-ohio-in-2012-galvanize-labor-unions/