Nice cute, clean, mathematically symmetrical theory. Pundits love it. Alas, there is no evidence it's true.
Elections are decided by who gets off their butts and votes and who stays home. No one changes their minds. Sorry to spread heresy among your easy theories.
There are a LOT of those voters. I had a hairdresser who wouldn't vote for Bush/Cheney because she thought Cheney was ugly. (I switched salons, needless to say.)
You really have to understand that a great deal of voting is not based on firm command of the issues. It is done often on feelings, impulse, peer pressure, and vague impressions derived from a few news stories and commercials. That is why the debates are important...often that is the only time voters actually listen to the candidates.
It is a shame that the electorate is so fickle and so ill-informed, but they are. And, their votes count just as much as yours does.