The term "Sept. 12 Republican" is sometimes used for this change; Dennis Miller and moviemaker David Zucker describe themselves this way. Numerous traditionally Democratic voters decided that Kerry and the DNC simply are not deep-down committed to ensuring that the US deals seriously with the terrorist threat. The fact that Howard Dean is now being seriously considered for DNC leadership simply reinforces this pacifist/isolationist image for the party.
Actor Ron Silver is another Sept 12th Republican, as you put it. I like the term, it certainly fits!