You want something to worry about? Consider this not implausible scenario:
Start with the New York Times interactive electoral map.
Award the swing states as follows: Ohio to Obama, Florida to Romney.
Give New Hampshire to Obama. New Hampshire has swung Republican only once since 1988, in 2000 -and then only because Ralph Nader won almost 4% of the vote. Give Wisconsin to Obama too. Wisconsin has not voted Republican in a presidential race since 1984, and there's little reason to think of Paul Ryan as a potent figure in state-wide Wisconsin politics.
Give Colorado, Virginia, Iowa, and Nevada to Romney.
What you then get is a 269-269 tie.
The contest is then tossed into the House of Representatives, where presumably Romney wins.
Now consider this: what if Obama has a lead in the popular vote? This moves us beyond Bush v. Gore territory into someplace even more contested and more frightening. And whereas 2000 was a low-intensity election involving a Democratic not hugely beloved by his own party base, a House contest in 2012 would unleash every passion in the American political system