Within twenty (20) days after the publication of any ordinance duly passed by the City, a petition may be presented to the council protesting against such ordinance continuing in effect. The petition shall contain the text of the ordinance and shall be signed by registered voters of the city equal in number to at least fifteen percent (15%) of the entire vote cast for all candidates for mayor at the last preceding general election at which a mayor was elected, which number shall in no case be less than two hundred and fifty (250). The ordinance shall thereupon and thereby be suspended from operation, and the council shall immediately reconsider the ordinance.
If the ordinance is not entirely repealed, the council shall submit the question of whether or not it shall become effective to a vote of the registered voters of the city, either at the next regular election or at a special election which may in its discretion be called for that purpose, and such ordinance shall not be restored to operation unless a majority of the registered voters voting at such election shall vote in favor thereof.
The procedure in regard to such petition of protest and referendum shall be the same as provided in this chapter for the initiative and referendum on a proposed ordinance, with such modifications as the nature of the case may require. Provided, however, that no such referendum shall be ordered by the council on any ordinance required to be passed by the general laws of this state, or when such ordinance shall be an emergency measure which is necessary for the immediate preservation of public peace, health, or safety.