Okla. Stat. tit. 26, § 26-12-106: Vacancies 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 even-

numbered 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 even-

numbered 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.