State Sen. Ethan Corson, left, and Sen. Cindy Holscher, both Johnson County Democrats, appear at an April 26, 2026, debate in Shawnee. They now are turning up the heat in their campaigns for the Democratic Party's nomination for governor by arguing about labor union endorsements and membership issues. A third candidate in that Aug. 4 primary is Overland Park Mayor Curt Skoog. (Photo by Sherman Smith/Kansas Reflector)TOPEKA — Kansas Democratic gu…