Here's the AP story from the home page. And here's an excerpt from Pence's letter to his colleagues, obtained by the Weekly Standard:
I am writing to inform you that, after much prayerful consideration, I have decided not to seek re-election as Chairman of the House Republican Conference.
As we consider new opportunities to serve Indiana and our nation in the years ahead, I have come to realize that it may not be possible to complete an entire term as Conference Chairman. As such, I think it would be more appropriate for me to step aside now, especially since there are other talented men and women in our Conference who could do the job just as well or better.
I do not know what the future holds for my little family, but I do know who holds the future. So for now, we will continue our duties serving the people of Indiana and do what we have always done in such times; we will wait on the Lord and follow where He leads. We certainly welcome your prayers and your counsel in the days ahead.
It's November 3rd. Let the Presidential Sweepstakes begin!
UPDATE: Or does Pence have slightly less lofty ambitions?