Republican Indiana Senator Dan Coats announced today that he is not running for reelection in 2016. Coats won the seat in 2010 after former Senator Evan Bayh retired. This was Coats' 2nd Senate stint. He was appointed to the Senate in 1989 to succeed Dan Quayle, who had resigned to become Vice President under George H.W. Bush. 

Prior to this announcement, the seat was favored to remain in Republican hands. It may become more competitive now and could be an additional hurdle to Republican retention of the Senate in 2016, as the party must defend 24 of the 34 seats up next year.