Kentucky Attorney General Jack Conway (D) announced Thursday that he'll run in the Democratic primary to challenge Sen. Jim Bunning (D-Ky.) The decision pits Conway against Lt Gov. Dan Mongiardo, who lost to Bunning in 2004 and has been endorsed by Gov. Steve Beshear (D).

"This is not a decision I reached easily," Conway said in a video on his website. "I've spoken with my family, community, and national leaders and many others I respect over the last several months. And I've been humbled by their encouragement and support."

Rep. Ben Chandler is also considering a run.