Okla. Stat. tit. 51, § 52

When sitting as a court of impeachment, the Senate shall be presided over by the Chief Justice, or if he is absent or disqualified, then one of the Associate Justices of the Supreme Court, to be selected by it, except in cases where all the members of said Court are absent or disqualified, or in cases of impeachment of any Justice of the Supreme Court, then the Senate shall elect one of its own members as a presiding officer for such purpose. The House of Representatives shall present all impeachments.