I looked to see if this has been posted yet and I didn't see it anywhere. I've asked myself "why don't they see what I see" so many times that I'm always really glad when I find a potential answer.
<snip>
To voters who identify strongly with a political party, the undecided voter is almost an alien life form. For them, a vote for Bush is a vote for a whole philosophy of governance and a vote for Kerry is a vote for a distinctly different philosophy. The difference is obvious to them, and they don’t understand how others can’t see it, or can decide whom to vote for on the basis of a candidate’s personal traits or whether his or her position on a particular issue “makes sense.” To an undecided voter, on the other hand, the person who always votes for the Democrat or the Republican, no matter what, must seem like a dangerous fanatic. Which voter is behaving more rationally and responsibly?
<snip>
http://www.newyorker.com/critics/atlarge/?040830crat_atlarge