Bush is hardly alone in this mispronunciation. It extends to pretty much the whole of the Republican party, really. I think it's one of those stupid bully things, trying to call somebody by something that's not really their name.
"Democratic", being the adjectival form of "democracy", is generally considered a positive term. "Democrat", on the other hand, refers to a person (or type of person), and can therefore be derided. They're basically trying to maneuver the language so condemning the party is easier.
no subject
no subject