In the case of a petition of the first class, if the owner does not file the stipulation within such 20 days, the political subdivision, within 60 days after the commission has made and filed its finding, shall commence an action in a court of competent jurisdiction to take such lands, property, and rights, under eminent domain proceedings. In the case of a petition of the second class, if the owner does not file the stipulation within such 20 days, the political subdivision, within 60 days after the commission has made and filed its finding, shall initiate proceedings for the purpose of submitting to its voters a proposition to acquire under eminent domain proceedings the lands, property, and rights. The political subdivision shall not be required, in either case, to delay for more than 20 days after the commission has made and filed its finding, before commencing such further proceedings. In the case of a petition of the second class, if the voters of the political subdivision, as provided by the law governing the political subdivision, vote in favor of any proposition to acquire under eminent domain proceedings, or otherwise, such lands, property, and rights, the political subdivision shall, within 60 days thereafter, commence an action in a court of competent jurisdiction to take such lands, property, and rights, under eminent domain proceedings, unless the owner has filed with the political subdivision a written stipulation consenting and agreeing to accept the just compensation fixed by the commission.