If Louisville is going to be a 1-party town then it should include everyone. The last day to register to switch parties is December 31, 2017. Fischer won by about 21,000 votes in his 2010 primary, which was the last time he ran opposed. There was a grand total of 50,000 Republican votes cast in the 2010 primary. If half of all Republican primary voters had instead voted against him in the Democrat party primary, then his opponent would have beaten him.