Sorry, but the religious Dukes of Hazzard watcher and the apolitical spouse are probably not going to vote at all.  If the a-olitical spouse DOES vote, he or she's probably going to just vote the same as his or her partner, regardless of which candidate is ahead.    

What you are saying is that Bush was perceived to be the winner by the vast majority of polls in 2000, therefore a certain number of undecideds voted for Bush "just because" he was the winner - yet Gore won the popular vote by half a million.  Where was this mythical break for the leader?  Where was it in 1996?  1992?  If you're so sure about it, show it to me.  I'm not going to take it on faith, like the Falwell and Bush followers, sorry.  

Here's an example to help you out: in the municipal elections here in Aracaju this year, the incumbent Deda was polling between 53% and 60% of the vote, with the principal challenger Susana getting between 19% and 20%.  The final vote tally, however, was 71% to 17%.  So, here there was a numerical break for the leader.  However, and this is a big however, voting in Brazil is mandatory, so all the apolitical losers who have no choice but to vote very likely do just vote for the leader, because the fact is that they don't care.  I just don't see it in the American Presidential numbers, though, because anybody who only votes for the "leader" is not going to vote at all.