No petition shall be accepted for filing pursuant to this article unless the signatures therein shall have been secured within six months of the date on which the first signature on the petition was affixed and such petition is submitted for filing as provided in Section 23515 within 60 days after the last signature is affixed. If the time between the date on which the last signature is affixed and the date on which the petition is submitted for filing exceeds 60 days, or, if any signature on the petition has been secured more than six months from the date on which the first signature was affixed, the petition shall be considered insufficient and shall be filed by the clerk as a public record without prejudice to the filing of a new petition.