The mayor shall be the presiding officer of the city council but shall not vote upon any question except in case of a tie and the mayor shall then cast the deciding vote. Except as otherwise provided herein or by ordinance, the mayor shall appoint the members of committees or commissions of the city. Within ten days after the council adopts an ordinance the mayor may sign it and shall thereupon take effect, or, the mayor may return it unsigned to the city recorder with a signed statement of objection, and the ordinance shall be deemed vetoed. If the mayor neither signs the ordinance nor submits a veto to the city recorder within ten days, the ordinance shall take effect at the end of ten days without the mayor’s signature. If the mayor vetoes an ordinance, the council may at its next regular meeting, or at a special meeting called for that purpose, reconsider the ordinance and, if two-thirds of the councilmembers present vote for such ordinance, it shall become immediately operative as though approved by the mayor.