(1) Signed petitions shall be filed with the city clerk for signature verification. Upon the filing of a petition, a city, upon passage of a resolution by the governing body of such city, and the county clerk or election commissioner of the county in which such city is located may by mutual agreement provide that the county clerk or election commissioner shall ascertain whether the petition is signed by the requisite number of voters. The city shall reimburse the county for any costs incurred by the county clerk or election commissioner. When the verifying official has determined that one hundred percent of the necessary signatures required by sections 18-2501 to 18-2537 have been obtained, he or she shall notify the municipal subdivision's governing body of that fact, and shall immediately forward to the governing body a copy of the petition.
(2) In order for an initiative or referendum proposal to be submitted to the governing body and the voters, the necessary signatures shall be on file with the city clerk within six months from the date the prospective petition was authorized for circulation. If the necessary signatures are not obtained by such date, the petition shall be void.