Any proposed ordinance may be submitted to the town council by a petition signed by qualified electors of the town equal in number to at least ten per cent of the number of persons registered to vote at the time of the last regular town election. Whenever the council receives a certified initiative petition from the town clerk, it shall proceed at once to consider the proposed ordinance transmitted therewith, and shall take a final vote on the enactment of same no more than thirty days following receipt of the petition from the town clerk. If the council shall fail to pass an ordinance thus proposed by initiative petition, or shall pass it in altered form, the said ordinance as originally proposed by the petitioners shall be submitted to the electors for their approval or rejection, not less than thirty days nor more than one year from the date the council takes its final vote thereon. The council may, and if no regular election is to be held within such period shall, provide for a special election.