If prior to the date when an ordinance takes effect a petition signed by qualified electors of the City equal in number to at least fifteen per cent of the total number of voters registered on the date of the last preceding regular municipal election, is filed with the City Administrator requesting that any such ordinance be repealed or be submitted to a vote of the electors, the ordinance shall thereby be prevented from going into operation. The council shall thereupon reconsider the ordinance at its next regular meeting, and either repeal it or by aye or no vote re-affirm its adherence to the ordinance as adopted. In the latter case the council shall immediately order a special election to be held thereon, or submit the ordinance at the next regular municipal election, pending which the ordinance shall remain suspended. If a majority of the electors voting thereon is opposed to the ordinance, it shall not become effective; but if a majority of the electors voting thereon favors the ordinance, it shall go into effect immediately or on the date therein specified.