President pro tempore of the Oklahoma Senate
The president pro tempore of the Oklahoma Senate is the second-highest-ranking official of the Oklahoma Senate and the highest-ranking state senator. The Oklahoma Constitution designates the Lieutenant Governor of Oklahoma as the highest-ranking official, serving ex officio as President of the Senate, even though the lieutenant governor only votes in the case of a tie.
Source: Wikipedia — President pro tempore of the Oklahoma Senate (CC BY-SA 4.0)