Except in the case of a grant to a public agency where the applicable law contains provisions for the election of the members of the governing body of the agency or where a county board of supervisors acts as the governing body of the agency, before a public agency may enter into a contract with the department for a construction loan or a grant under this chapter, the public agency shall hold an election on the proposition of whether or not the public agency shall enter into the proposed contract and more than 50 percent of the votes cast at such election must be in favor of such proposition; provided, that if a higher percentage of favorable votes is required for the issuance of any bonds by the public agency or is required by the Constitution before the public agency may incur an indebtedness, such higher percentage shall apply in lieu of the percentage set forth in this subdivision.