If before the date tentatively set for the authorization of the issuance of time warrants applying to a contract covered by this subchapter or if before that authorization a petition signed by at least five percent of the registered voters of the county is filed with the county clerk protesting the issuance of the time warrants, the county may not issue the time warrants unless the issuance is approved at an election ordered and conducted in the manner provided for county bond elections under Chapter 1251, Government Code.