1. North Carolina—Recent polls show Obama in a dead heat with McCain. The last time North Carolina voted for a Democratic president was Jimmy Carter in 1976.
2. Florida—The Real Clear Politics average puts Obama ahead only by 1.8 points. A close race in a state with a history of voting issues (most notably the 2000 recount fiasco) could potentially be drama-filled.
3. Pennsylvania—Polls in Pennsylvania have tightened in the last week, making it an especially important state to watch. Nate Silver at Five Thirty Eight thinks that if Obama wins Pennsylvania, he will have clinched the election.
4. Virginia—No Democratic presidential candidate has won the state since 1964. Recent polls show a narrow margin between the candidates. If McCain loses here, he will have a difficult time winning the election.
5. Ohio—In this battleground state, Obama has a significant lead among early voters. If Republican turnout is not high on the day of the election, McCain may not be able to make up those early votes that he lost.