It's a losing battle... Every time something like this arises, you have people over-reacting, saying they won't vote for Bush, saying there's no difference between the parties (what a moronic view)... When they see the stark differences between Dean's and Bush's policies and views, they'd be utter fools to vote for Dean, or equally as bad, sit on their hands during the election.
This knee-jerk reaction, while not surprising, is nevertheless disappointing.