Who knows what someone blowing a billion of their own bucks could pull off, but there is no national Bloomberg constituency at the moment. Except, as Eric put it:
Those who support the idea of his candidacy are either people who stand to see some of that $1 billion he'll be handing out if he runs; fools and naifs of the sort that supported Nader, albeit of the right-center rather than the far-left; people who hate Democrats and want to elect a Republican but cannot, either for personal or professional reasons, admit this. (See under "Broder, David.")