After the appointment of the initial board, the board shall administer subsequent elections for members of the board with the assistance of the secretary. Before the expiration of a member’s term of office, the board shall nominate any number of producers as candidates for the membership position for which an election is to be held. The board shall nominate candidates based on criteria established by the board. Additional candidates may be nominated by a written petition signed by twenty-five producers. The petition shall be in a form and delivered to the board as required by the board.