By Rick HowlettKentucky Attorney General Jack Conway has gained ground on Lt. Governor Dan Mongiardo in the Democratic primary for U.S. Senate, according to the latest Courier-Journal/WHAS11 Bluegrass Poll.The poll, conducted by Survey USA, gives Mongiardo a three-point lead over Conway, 35 percent to 32 percent. The margin of error is 3.9 percent.The previous poll, conducted in March, gave Mongiardo an 18-point lead.The paper points out that Conway has been advertising on television in recent weeks while Mongiardo has not.Twenty-one percent of the Democrats surveyed were undecided.On the Republican side, Bowling Green eye doctor Rand Paul maintains a 15-point lead over Secretary of State Trey Grayson, with 19 percent undecided.