Rand Paul, son of Texas Rep. Ron Paul, is in a close race with Kentucky Secretary of State Trey Grayson for the GOP Senate nomination, with Paul leading 35 percent to 32 percent. Six percent favored three other candidates, 10 percent said they preferred another choice and 18 percent were undecided, according to a SurveyUSA poll conducted Oct. 30 - Nov. 2. The margin of error is 4.7 points.

Grayson does better than Paul when matched up against two potential Democratic candidates in the general election.

The two are contending to run for the seat being vacated by three-term Republican Jim Bunning who announced his retirement this summer in the face of a meager fundraising effort and the threat of a primary challenger.

Paul, an eye surgeon, leads Grayson among conservatives by 39 percent to 31 percent. Conservatives made up 69 percent of the sample in the SurveyUSA poll. Among moderates, who made up 21 percent of the sample, Grayson leads by 36 percent to 24 percent. Liberals comprised only 6 percent of the sample.

There is a clearer frontrunner on the Democratic side, with Lt. Gov. Dan Mongiardo leading Attorney General Jack Conway by 39 percent to 28 percent with 8 percent shared by three other candidates, 10 percent preferring someone else and 16 percent undecided. The two are tied among Democrats who describe themselves as conservative (26 percent of the sample), but Mongiardo holds double-digit leads among moderates and liberals who, together, comprise 64 percent of the sample.

In general election match-ups, Paul leads Conway 44 percent to 39 percent and ties with Mongiardo. Republican Grayson leads Conway 43 percent to 49 percent and Mongiardo 48 percent to 38 percent.