Every amendment to a city charter whether passed pursuant to the provisions of this act or heretofore granted or passed by the state legislature for the government of such city, before its submission to the electors, and every charter before the final adjournment of the commission, shall be transmitted to the governor of the state. If he shall approve it, he shall sign it; if not, he shall return the charter to the commission and the amendment to the legislative body of the city, with his objections thereto, which shall be spread at large on the journal of the body receiving them, and if it be an amendment proposed by the legislative body, such body shall re-consider it, and if 2/3 of the members-elect agree to pass it, it shall be submitted to the electors. If it be an amendment proposed by initiatory petition, it shall be submitted to the electors notwithstanding such objections.