Vacant elective offices in the city shall be filled by appointment. A majority vote of the council shall be required to validate the appointment. The appointee’s term shall begin immediately upon his appointment and shall continue until the beginning of the year following the next general biennial election and until his successor is qualified, and his successor for the unexpired term shall be chosen at the next general biennial election after the said appointment. During the temporary disability of any officer or during his absence temporarily from the city for any cause, his office may be filled protem in the manner provided for filling vacancies in the office permanently.