The election of the Mayor and all City councilors and school commissioners shall be by ballot, and the person or persons receiving a plurality of all votes cast for any office aforesaid shall, except as hereinafter provided, be declared elected thereto. However, if no person receives at least 40 percent of all votes cast for any office aforesaid, no one shall be declared elected and a runoff election shall be held. The only candidates in the runoff election shall be the two persons receiving the greater number of votes or, in case of a tie, the persons receiving the greatest number of votes or the persons receiving the second greatest number of votes. The Chief Administrative Officer shall within seven days warn a runoff election to be held not less than 12 days nor more than 20 days after the date of the warning. The warning shall be published in a newspaper of general circulation in the City and posted in a public place. The person or persons receiving a plurality of all the votes cast in a runoff election shall be declared elected. (Amended 2005, No. M-3, § 2, eff. May 12, 2005; 2009, No. M-17 (Adj. Sess.), § 2, eff. April 24, 2010.)