As votes accumulate, Bush's percentage will slip even if his lead stays the same in number of votes.
In other words:
Bush 100,000; Kerry 50,000 is Bush 67%; Kerry 33%
Bush 250,000; Kerry 200,000 is Bush 60%; Kerry 40%
DOOOOHHHH! I meant that to be Bush 150,000; Kerry 100,000 but I screwed up!
Still, you all get my point! :-)