Amendments to this charter may be submitted to the electors of the City by a two-thirds vote of the City Commission, and, upon petition signed by ten percent of the electors of the City, setting forth any such proposed amendment, shall be submitted by such City Commission. The ordinance providing for the submission of any such amendment shall require that it be submitted to the electors at the next regular municipal election, if one shall occur not less than sixty nor more than one hundred and twenty days after its passage. Otherwise it shall provide for the submission of the amendment at a special election to be called and held within the time aforesaid. Not less than thirty days prior to such election, the Clerk of the City Commission shall mail a copy of the proposed amendment to each elector whose name appears upon the polls or registration books of the last regular or general election. If such proposed amendment is approved by a majority of the electors voting thereon, it shall become a part of the charter at the time fixed therein.