(1) Any labor organization, employee, or group of employees may file a petition to intervene within ten days of the first day of posting of the notice of decertification proceedings.

(2) The petition shall be accompanied by proof of interest, consisting of authorization cards, or copies thereof, from at least ten percent of the employees in the unit. The cards shall indicate that the signatories do not desire to be represented for collective bargaining purposes by the current board-certified or employer-recognized exclusive representative, and the cards shall identify the signatories' choice of a new exclusive representative.

(3) The petition to intervene shall conform in all other respects to the requirements for a UD petition.

(4) The board agent shall review the petition and the authorization cards for compliance with these rules and serve a copy of the petition to intervene upon all other parties.