10 ILCS 22/5-20

In submitting this State's certificate of ascertainment as required by 3 U.S.C. 6, the Governor shall certify this State's electors and state in the certificate that: (1) the electors will serve as electors unless a vacancy occurs in the office of elector before the end of the meeting at which elector votes are cast, in which case an alternate elector will fill the vacancy; and (2) if an alternate elector is appointed to fill a vacancy, the Governor will submit an amended certificate of ascertainment stating the names on the final list of this State's electors.