History and the 2014 elections
According to the Washington Post, patterns from past senate elections can help us predict what will take place this fall:
The Wall Street Journal this week dove into the data to try and figure out what the past might tell us about the immediate future. That is, what the uneven pattern of Senate races might suggest about the November elections. Among the charts was a variant of the one below, showing that, over time, the winners of Senate races have less and less frequently been from the opposite party as the winner of the most recent presidential race in that state.