On:
(1) The first Monday in December of each even-numbered year; and
(2) Its first regular meeting in December of each odd-numbered year,
the board of commissioners shall choose one of its members as chairman for the ensuing year, unless the chairman is elected as such by the people or otherwise designated by law. The board shall also at that time choose a vice-chairman to act in the absence or disability of the chairman. If the chairman and the vice-chairman are both absent from a meeting of the board, the members present may choose a temporary chairman.
The chairman is the presiding officer of the board of commissioners. Unless excused by rule of the board, the presiding officer has the duty to vote on any question before the board, but he has no right to break a tie vote in which he participated.