Within thirty (30) days after the enactment by the Council, of any ordinance or resolution which is subject to a referendum under the laws of the State of Ohio, a petition signed by no less than ten percent (10%) in number of the total electors voting at the last regular municipal election may be filed with the Council, requesting the ordinance or resolution be repealed or submitted to a vote of the electors. When such petition is filed the Clerk of the Council shall promptly determine the sufficiency of the petition, and if found sufficient, the Council shall thereupon, within thirty (30) days of the filing of such petition reconsider such ordinance or resolution. If the Council fails to repeal said ordinance or resolution within thirty (30) days of the filing of such petition the Council shall submit it to a vote of the electors at the next general or regular municipal election occurring more than ninety (90) days after the filing of such petition, but if such petition is signed by at least twenty percent (20%) in number of such electors, the date of the election may be fixed therein, which may be a special election to be held at any time more than ninety (90) days after the filing of such petition.