Comer said Tuesday night that he would seek a recanvass. Unofficial returns showed him in a virtual tie with businessman Matt Bevin.
Republicans Hal Heiner and Will T. Scott conceded early.
There is no runoff election in Kentucky, and no automatic recounts. State law allows for recanvassing only if a county clerk or a county board of elections notices a discrepancy or if a candidate makes a written request to the Secretary of State.
Comer says he owes it to his supporters to request a recanvass. However, he says he told Bevin that he would help get him elected in November if Bevin is ultimately declared the winner.