This is a big bummer. He would have made Lugar spend some time and energy defending his seat at least.
From http://www.howeypolitics.com/:
I have been honored by the many friends and fellow Hoosiers encouraging me to run for the U.S. Senate these past few weeks. I have considered this option because I believe each of us has a role to play in making our nation safer, more prosperous, and with ample opportunities for all Americans. But thinking of my four young children reminds me that, at this important stage in their lives, my most important job is to be the best husband and father I can possibly be.