Career
The district included the affluent areas of Indian Hills and Prospect. He was defeated in the 1988 primary election for re-nomination to the state House by his fellow Republican, Susan Bush Stokes. Guenthner was the Republican nominee for the United States Senate from Kentucky in 1978.
He lost to the incumbent Democrat Walter Huddleston.
Six years later, Mitch McConnell, also of Jefferson County, upset Huddleston, who then became a Washington, District of Columbia,-based lobbyist. Guenthner also made an unsuccessful run for Jefferson County judge-executive in 1985.