NPR reports:

Sen. Jim Bunning, a two-term conservative Republican from Kentucky who has been plagued by party infighting, poor fundraising and weak polling numbers, announced today he will not seek re-election in 2010.

Bunning in fact blamed his fellow Republicans for standing in his way, with a veiled slap at fellow Kentuckian Mitch McConnell, the Senate GOP leader, who has made it clear for quite some time that he wanted Bunning to retire.

I had hoped Bunning was crazy enough to stay. Now it will likely become a really tough fight for the Kentucky Dems. 

Update: dakine01 has more.