The officers of the public disclosure commission shall be chair and vice chair. Their terms shall be one year or until a successor is elected. Elections to fill commission offices shall be held annually at the regular June meeting of the commission, or at a special election called for that purpose between May 1st and June 30th of the calendar year in which the new terms will commence. Vacancies in said offices may be filled by a vote of the commission at any regular meeting or any special meeting called for that purpose.