In any contested case, the commission may direct that the proceedings or any part thereof shall be heard by a hearing examiner to be appointed by the commission; provided, that only the members of the commission and the regular employees of the commission shall be eligible to serve as such examiners. Proceedings before hearing examiners shall be according to this chapter, other applicable laws and the rules of the commission. Whenever a contested case, or any part thereof, is heard by a hearing examiner, the hearing examiner shall make a proposal for decision in writing which shall include findings of fact and conclusions of law made by the hearing examiner. Such proposals for decisions shall be served on all parties of record, and each party who would be adversely affected by the proposed decision shall be given an opportunity to file exceptions and present argument in writing to the commission itself. Before the commission shall enter a final order in such cases, the members thereof shall personally consider the entire record, or such portion thereof as may be cited by the parties, and shall make its decision in the form and manner prescribed by this chapter for decisions in contested cases.