With his support for Bruce Lunsford and Greg Stumbo, Sen. Julian Carroll has apparently earned himself a primary opponent (or two) in 2008.
The most likely candidate would have to be Joe Graviss, who lost to Carroll in the 2004 primary. Expect a more liberal candidate to jump in as well.
Update: Looks like Bluegrass Report was having the same thought about Graviss. Will Rep. Ben Chandler weigh in too?