Oklahoma constitution
Article V: legislative power
Section 11a

The apportionment of the Legislature shall be accomplished by the Legislature according to the provisions of this article, within ninety (90) legislative days after the convening of the first regular session of the Legislature following each Federal Decennial Census. If the Legislature shall fail or refuse to make such apportionment within the time provided herein, then such apportionment shall be accomplished by the Bipartisan Commission on Legislative Apportionment, according to the provisions of this article. The Commission shall be composed of seven (7) members as follows: the Lieutenant Governor, who shall be nonvoting and the chair of the Commission; two members, one Republican and one democrat, appointed by the President Pro Tempore of the Senate; two members, one Republican and one democrat, appointed by the Speaker of the House of Representatives; and two members, one Republican and one democrat, appointed by the Governor.