Candidates for elective offices shall be nominated in accordance with ORS 221 190, as the same may be amended, except that petitions or certificates of nomination provided for in such law must be filed with the city recorder, not later than 20 days before the election. Such mode of nomination shall remain effective until such time as the council by ordinance provides other lawful methods of nomination. The council is hereby expressly authorized to provide such other lawful methods of nominations.