Public Policy Polling (5/1-2, likely voters, 12/18-21/2009 in parens):
Rand Paul (R): 46 (44)
Trey Grayson (R): 28 (25)
Undecided: 21 (32)
Other: 4
(MoE: ±5.1%)
Jack Conway (D): 27 (37)
Dan Mongiardo (D): 36 (33)
Undecided: 27 (30)
Other: 10
(MoE: ±4.6%)
PPP finds Paul ahead by a mile in the Republican primary -- quite the contrast with Grayson's internal polling which purports to show a tied race. Still, Grayson's camp isn't going down without a fight -- they just unfurled an endorsement (and accompanying ad) from Mitch McConnell. (Though the only surprising thing about that is the fact that McConnell was officially neutral for so long.)
On the Democratic side, you have to wonder if Conway has a fighting chance. In his favor, a greater share of primary voters consider Conway to be a blank slate: 51% have no opinion of him, while 36% react the same way to Mongiardo. Perhaps Conway can close the gap by flooding the zone with his superior cash reserves in the final two weeks of the race, but it'll be tough.
http://www.swingstateproject.com/diary/6834/kysen-paul-mongiardo-in-the-lead