One possibility in the election: Both candidates get 269 electoral votes, resulting in a tie. From Napp Nazworth:
In a Thursday blog post, University of Virginia political scientists Larry Sabato, Kyle Kondik and Geoffrey Skelley point out that a tie in the electoral college, 269-269, is a real possibility.
For the Electoral College to end in a tie, Romney would win Colorado, Florida, Iowa, Nevada, North Carolina, and Virginia. Obama would win Michigan, New Hampshire, Ohio, Pennsylvania, Wisconsin.
Given recent polls, this scenario is not hard to imagine. It shows each candidate winning states where polls show them polling slightly better than their opponent, with one exception — Nevada. Sabato, Kondik and Skelley point out that of all the states on the 269-269 map, Romney winning Nevada is the least likely.