Don Surber discusses why John McCain is having problems. I think that his success in foisting McCain-Feingold on the rest of us was the death knell for his presidential hopes. In essence, he tried to silence us, and he went to the mat to do so. It was the ultimate disrespect. Romney and Giuliani disagreed, but the former is taking great pains to not insult people who disagree with him, and Giuliani has been honest about the disagreement.
Ultimately, John McCain traded the Presidency for McCain-Feingold.