(a) In a city of the first class, the mayor or his duly authorized representative may approve for payment out of funds previously appropriated for that purpose, or disapprove, any bills, debts, or liabilities asserted as claims against the city.
(b) The municipal governing body shall, by ordinance, establish in that connection a maximum amount, and the payment or disapproval of such bills, debts, or liabilities exceeding that amount shall require the confirmation of the governing body.