By Rick HowlettDemocrat Greg Fischer and Republican Chris Thieneman hold narrow primary leads in a Courier Journal/WHAS11 Bluegrass Poll of voters in the Louisville mayor's race published today, but many of those surveyed say they're undecided about the election.Twenty percent of Democratic voters surveyed said they would cast their ballot for Fischer. Metro Councilman David Tandy is second in the poll with 17-percent followed by Jim King, also a Metro Councilman, with 12-percent. Tyler Allen is fourth, with eight percent, followed by Burrel Farnsley (4%), Lisa Moxley (3%), Connie Marshall (2%) and Shannon White (2%). The Democratic poll has a 3.9-percent margin of error and 32-percent of the voters say they're undecided.On the Republican side, 34-percent of those surveyed said they would vote for Thieneman, a Louisville developer. Metro Councilman Hal Heiner is second with 30-percent and business owner Jonathon Robertson is third with six-percent. The GOP poll has a 4.7-percent margin of error and 30-percent of those surveyed say they're undecided.The poll of 656 likely Democratic primary voters and 449 likely Republican voters was conducted by SurveyUSA.