Quote from Cache Landing:
Various reasons I'm sure. Some don't like his religion. Many don't like him for the fact that he doesn't form political alliances as readily.
He obviously doesn't have the support of the republican establishment because he continually screams that it is not the president but "Washington" that is broken. He realizes something that few will admit. Our president doesn't have that much power if "Washington" doesn't align behind him.
The other candidates specifically didn't like two things about him.
1) He criticized them on his own weak spots. That is politics 101. If you are a little weak on a certain point, but your opponent is weaker, then go after that point before they mention your own weakness.
2) The other main point is his money. Not that he has the money but how he uses it. He loved contrast adds. He took his opponents' actual positions and contrasted them to his own better looking positions, of course without mentioning anything even slightly negative about himself. His opponents called them attack adds, but in reality they were simple contrast adds. The problem for his opponents was that for every single add they ran about him, he could run five more about them. Not exactly a fair playing field. So they ganged up on him.
I think this is accurate, but in retrospect i believe he made a big mistake by being too negative. He should have concentrated on convincing voters that he was the best, not trying to tear down other republicans. Let the talk shows and surrogates do the attacking. It turned out that he made a big push to get the hard core conservative vote, but the way the primary caldendar worked, the early states up through super tuesday were not really decided by conservatives. They were decided by independents and moderates. The conservative vote was split several ways.
Bottom line, his campaign was not really that well run. It was well-financed, and I think they tried to substitute money for strategy. The sad thing is, he had a compelling personal story and message. He just wasn't that authentic as the new Reagan, and voters never warmed up to him. They saw a rich guy trying to buy the nomination.