Ill. Admin. Code tit. 56 § 5300.1305
In the absence or disability of the Chair, the Vice-Chair shall perform temporarily all duties of the Chair, and when so acting shall have all the powers of, and be subject to all restrictions upon, the Chair. In the event of the Chair's inability to act, the Commission shall elect a new Chair at the next regular or special meeting to serve until the expiration of the term of the succeeded Chair. The Vice-Chair shall be selected by the members of the Commission by majority vote. If the office of Vice-Chair is vacated before the expiration of a term, it shall remain vacant until the next regular meeting, at which time the Commission shall elect a new Vice-Chair to serve until the expiration of the term of the succeeded Vice-Chair.
Ill. Admin. Code tit. 56, § 5300.1305