§ 26 O.S. § 26-12-106Vacancies in the Legislature

A. Whenever a vacancy shall occur in the office of a member of
the State Senate or the State House of Representatives, the vacancy
shall be filled at a Special Election to be called by the Governor
within thirty (30) days after the vacancy occurs; provided, no
special election shall be called if the vacancy occurs in an evennumbered year if the term of the office expires the same year.
B. If in an even-numbered year an incumbent State Senator with
two (2) or more years remaining in the term for which elected shall
file with the Oklahoma Secretary of State before March 1 a
resignation in writing which states that the resignation will not
become effective immediately, but rather will become effective on
some date certain that is after the General Election but before the
convening of the next session of the Legislature, the vacancy shall
be filled by a special election which shall be held in that evennumbered year on the same dates as the regular Primary Election,
Runoff Primary Election and General Election. The filing period for
the special election shall be the regular filing period prescribed
in Section 5-110 of this title. The person elected in the General
Election of the special election shall take office on the date the
resignation of the incumbent becomes effective and shall serve the
remainder of the unexpired term.