McCain's was previously unable to convince the base he was sufficiently their man and was only barely able to dissociate himself from Bush. In the past weeks, he has almost entirely escaped Bush, and has picked up everyone he needs in the religious core.

In other words, he has the entire 04 bloc + people who wouldn't vote for Bush at this stage but still consider themselves republicans + closet racists dems (a constituency I think everyone is undercounting).