I hate to defend Hillary but...she won the overwhelming majority of primaries and still didn't get the nomination. At the end she won Texas WV, KY, OH, PA, and still lost. They know that this nomination was stolen from them by the party and the press and they can't get over that resentment.
McCain wasn't my 1st or 2nd or 3rd pick but I never felt that he stole anything. I never felt that the party screwed my candidate. And then he turned the heat up on what was my lukewarm support by picking Sarah Palin! Contrary to popular opinion, McCain hasn't done everything wrong this campaign.
That sounds plausible. It wouldn't be enough for me to abandon my core beliefs, but the other side is crazy, so maybe.