20 ILCS 5/5-605
Each officer whose office is created by the Civil Administrative Code of Illinois or by any amendment to the Code shall be appointed by the Governor, by and with the advice and consent of the Senate. In case of vacancies in those offices during the recess of the Senate, the Governor shall make a temporary appointment until the next meeting of the Senate, when the Governor shall nominate some person to fill the office, and any person so nominated who is confirmed by the Senate shall hold office during the remainder of the term and until his or her successor is appointed and qualified. If the Senate is not in session at the time the Code or any amendments to the Code take effect, the Governor shall make a temporary appointment as in the case of a vacancy.
During the absence or inability to act of the director or secretary of any department, or in case of a vacancy in any such office until a successor is appointed and qualified, the Governor may designate some person as acting director or acting secretary to execute the powers and discharge the duties vested by law in that director or secretary.
During the term of a General Assembly, the Governor may not designate a person to serve as an acting director or secretary under this Section if that person's nomination to serve as the director or secretary of that same Department was rejected by the Senate of the same General Assembly. This Section is subject to the provisions of subsection (c) of Section 3A-40 of the Illinois Governmental Ethics Act.
20 ILCS 5/5-605