Rule 2.7. Speaker Pro Tempore; election
The Speaker Pro Tempore of the House of Representatives shall be elected by the membership of the House from among the members thereof in the same manner as the Speaker. He shall be elected every four years at the time the Speaker is elected and his election shall be the next order of business following the election of the Speaker. He may be removed from office in the manner provided for removal of the Speaker. Vacancies in the office of Speaker Pro Tempore shall be filled in the manner of the original selection.
Mason's Manual: Sec. 556
HR 3, 1973.