Promptly after the grounds for such motion become known, the state or the defendant may move for a change of judge on the ground that the presiding judge is biased or prejudiced against the state, the attorney for the state, the defendant or the defendant’s attorney. The motion shall be supported by affidavits stating sufficient facts to demonstrate such bias or prejudice. Prior to a hearing on the motion other affidavits may be filed. The motion shall be referred to another judge, or a court commissioner, who shall rule on the motion, and if granted shall immediately assign the case to a judge other than the disqualified judge. A ruling on a motion for a change of judge is not an appealable order, but the ruling shall be made a part of the record, and may be assigned as error in an appeal of the case or on a bill of exceptions.