Neb. Rev. Stat. § 70-1313

If a party to the dispute fails or refuses to appoint its arbitrator within the time established in section 70-1309 , the arbitrator appointed by the other party shall, within ten days after such failure apply to the American Arbitration Association for the appointment of the second arbitrator. Within ten days after the appointment of the second arbitrator, the two arbitrators so selected shall appoint a third arbitrator.