Jim Bunning's retirement is intuitively good news for Republicans but our polling data backs it up too.
In April we found that:
-Jack Conway led Bunning 42-33 but Trey Grayson only 37-33
-Dan Mongiardo led Bunning 43-36 but trailed Grayson 40-36
So the race goes from one that Democrats almost certainly would have won to one that will start out as a tossup.