Of course it's possible. But I think it's highly unlikely. I suppose one possibility is that McCain solidifies himself in the west, winning Colorado, New Mexico and Nevada...while garnering just enough support in northern and central Pennsylvania to swing the Keystone state to his camp. He would, of course, have to win Ohio also...
But here's another unlikely, improbable, but not completely impossible scenario...Barack wins Virginia, Colorado and Pennsylvania. But New Hampshire Democrats stay home and Wisconsin really is tilting Republican....
Poll
