In most battleground states 5-10 percent of voters are either undecided or voting for a third party.

So, let's take the average, and say that 7 out of every 100 voters are undecided or third party voters.

Give me your prediction of what those 7 voters will do.

My prediction:
2 vote for McCain
1 vote for Obama

1 vote for a third party
3 dont vote (either because they forget, dont care and stay home, or dont care and go to the polls anyway, but see the long lines and say "forget it."

In this case, McCain isnt able to recover enough votes to win.