A third Republican has entered the race for U.S. Senator Jim Bunning's seat.Todd County businessman Bill Johnson joins Bunning and retired engineer Roger Thoney as declared candidates in the 2010 GOP primary.Kentucky Secretary of State Trey Grayson and Bowling Green optometrist Rand Paul have both formed exploratory committees for a possible race, but they say they won't run unless Bunning drops out."I certainly invite them to join," Johnson says. "They have their exploratory committees and they're out raising funds but I would like to see them get in the race. Let's see where they stand on the issues, let's talk about the issues and let's see who's best able to represent the needs of Kentucky."Johnson says he understands their reluctance to face the two-term senator, but he decided last month not to wait for other opponents to enter the race."And I also thought the Senate seat was an important seat. It was one we have to keep as Republicans. I respect Senator Bunning a lot, but I think it is time for new leadership."Johnson says he needs to raise about $200 thousand by the end of the year to compete."I'm going to run a very fiscally conservative campaign," he says. "What I have always thought to be very interesting is that many candidates will talk about fiscal conservatism, yet they will spend enormous sums of money trying to reach the office."State Senate President David Williams has also expressed interest in the primary.On the Democratic side, Attorney General Jack Conway, Lieutenant Governor Daniel Mongiardo and former customs agent Darlene Fitzgerald Price are all in the race.