This isn't that surprising:
http://indypolitics.org/...
U.S. Senator Dan Coats has just informed Indy Politics that he will NOT run for another term in the U.S. Senate.
Coats said he deliberated for months before making his decision. He says he informed leadership this morning today of his decision.
When asked why he decided not to run, Coats said he would have to spend the next two years campaigning instead of playing a vital role in the Senate. In addition, had he won re-election he would be nearly 80 by the end of his second term. - Indy Politics, 3/24/15
The Hoosier State is a red state so I'm sure there will be plenty of Republicans lining up for this race. We could always get lucky and get another Richard Mourdock but we shall see. Former Senator Evan Bayh (D. IN) isn't a firm no. You can read more here:
http://www.dailykos.com/...
We shall see.