Oregon Constitution Art. II § 14a

Incorporated cities and towns shall hold their nominating and regular elections for their several elective officers at the same time that the primary and general biennial elections for State and county officers are held, and the election precincts and officers shall be the same for all elections held at the same time. All provisions of the charters and ordinances of incorporated cities and towns pertaining to the holding of elections shall continue in full force and effect except so far as they relate to the time of holding such elections. Every officer who, at the time of the adoption of this amendment, is the duly qualified incumbent of an elective office of an incorporated city or town shall hold his office for the term for which he was elected and until his successor is elected and qualified. The Legislature, and cities and towns, shall enact such supplementary legislation as may be necessary to carry the provisions of this amendment into effect.