The Republicans control the State Senate in Kentucky - Williams has been the Senate president for some time.
However...I don’t think repeal of the 17th amendment is one of those issues not easy to explain and doesn’t make sense to make as an issue as a campaign for governor - it can only be used against him later in ads saying “Williams wants to take away your right to vote!” This was, politically, not a wise move.
Williams has already lost a race for the U.S. Senate himself, maybe it was to Wendell Ford prior to Bunning.