Liberals in blue states are not going to vote for him. They'll vote for the RAT!
Reagan benefited from a weak and dimwitted opponent (a luxury we are unlikely to have in 2008) to get liberal Massachusetts and 48 other states to vote for him.
The 2000/2004 political boundaries are not set in stone, and it is foolish to think that a different candidate will not appeal to different voters.
But my main point is that “electability” is not always a good thing, and I for one think we can do a lot better and still win.
Too, the only states he would make competitive are the ones that should be solidly GOP.