A mediator may be used in the collective bargaining process whenever: the Commission and the employee organization agree to mediation; or an impasse results, and the Commission or the employee organization requests mediation. The mediator shall be selected jointly by the Commission and the employee organization from a list supplied by the American Arbitration Association or the Federal Mediation and Conciliation Service. If the Commission and the employee organization are unable to agree on the selection of a mediator, the labor relations administrator shall select the mediator. The Commission and the employee organization shall share equally the costs of mediation.