Nominations for elective offices of the City shall be made only by petition, signed by registered electors of the City not less in number than 3% of the number voting at the last preceding general election, and shall be accompanied by the written acceptance of the nominee. The nomination of each candidate shall be made by a separate petition. No primary election shall be held for the selection of any candidate for any elective office of this City; and no nomination for any such office shall be of any effect unless made as required by this Section 1. The ballot used in the election of officers of the City shall be without party mark or designation. The names of all candidates for any City office shall be placed upon the same ballot and shall be rotated in the manner provided by the laws of Ohio. Except as otherwise provided in this Charter, the laws of Ohio shall govern the nomination and election of the elective officers of this City.