ORS § 221.353
No judge of a municipal court having two or more judges shall hear to try any action, matter or proceeding if a party thereto or an attorney appearing therein moves the court for a change of judge on grounds of prejudice. The motion shall be supported by an affidavit stating that the judge before whom the action, matter or proceeding is pending is prejudiced against the party or attorney, and that the affiant or the client of the affiant cannot or believes that the affiant or the client of the affiant cannot have a fair and impartial trial or hearing before the judge, and that such motion is not filed for the purpose of delay. The motion shall be filed before the action, matter or proceeding is to be tried or heard. No party or attorney shall make more than one application in any action, matter or proceeding.
ORS 221.353