Such charter so ratified and adopted may be amended, or a charter convention called, by a proposal therefor made by the law-making body of such city or by the qualified electors in number not less than five per cent of the next preceding gubernatorial vote in such city, by petition filed with the council or governing authorities. The council or governing authorities shall submit the same to a vote of the qualified electors at the next general or special election not held within thirty days after such petition is filed. In submitting any such charter or charter amendments, any alternative article or section may be presented for the choice of the voters and may be voted on separately without prejudice to others. Whenever the question of a charter convention is carried by a majority of those voting thereon, a charter convention shall be called through a special election ordinance, and the same shall be constituted and held and the proposed charter submitted to a vote of the qualified electors, approved or rejected, as provided in Section two hereof. The City Clerk of said city shall publish with his official certification, for three times, a week apart in the official paper in said city, if there be one, and if there be no official paper, then in at least one newspaper, published and in general circulation in said city, the full text of any charter or charter amendment to be voted on at any general or special election.

No charter or charter amendment adopted under the provisions of this amendment shall be amended or repealed except by electoral vote. And no such charter or charter amendment shall diminish the tax rate for state purposes fixed by act of the Legislature, or interfere in any wise with the collection of state taxes.