10 ILCS 5/10-11
Any vacancy in the nomination of a new political party candidate occurring prior to the date of certification of candidates for the ballot by the certifying board or officer must be filled prior to the date of certification. The resolution to fill such vacancy shall be sent by U.S. mail or personal delivery to the certifying officer or board within 3 days of the action by which the vacancy was filled; provided, if such resolution is sent by mail and the U.S. postmark on the envelope containing such resolution is dated prior to the expiration of such 3 day limit, the notice or resolution shall be deemed filed within such 3 day limit. Failure to so transmit the notice or resolution within the time specified in this Section shall authorize the certifying officer or board to certify the original candidate. Vacancies shall be filled by the new political party officers.
Any vacancy in nomination occurring after certification but prior to 15 days before a regular election shall be filled by the new political party officers within 8 days after the event creating the vacancy in the manner heretofore prescribed.
The resolution to fill a vacancy in nomination shall be duly acknowledged before an officer qualified to take acknowledgements of deeds and shall include, upon its face, the following information:
The resolution to fill a vacancy in nomination shall be accompanied by a Statement of Candidacy, as prescribed in Section 10-5, completed by the selected nominee and a receipt indicating that such nominee has filed a statement of economic interests as required by the Illinois Governmental Ethics Act.
The provisions of Sections 10-8 through 10-10.1 relating to objections to certificates of nomination and nomination papers, hearings on objections, and judicial review, shall apply to and govern objections to resolutions for filling a vacancy in nomination.
Any vacancy in nomination occurring 15 days or less before a regular election shall not be filled. In this event the certification of the original candidate shall stand and his name shall appear on the official ballot to be voted at the election.
A vacancy in nomination occurs when a candidate who has been nominated under the provisions of Section 10-2 dies before the election, or declines the nomination; provided that nomination may become vacant for other reasons.
However, the provisions of this Section shall not apply to any vacancy in nomination for a municipal office for which the Municipal Code, as now or hereafter amended, provides a different method for filling such vacancy, and the applicable provision of the Municipal Code shall govern in such cases.
Any vacancy in a nomination by caucus of an established political party for a township or municipal office shall be filled in accordance with Section 7-61 of this Code.
For purposes of this Section, the words "certify" and "certification" shall refer to the act of officially declaring the names of candidates entitled to be printed upon the official ballot at an election and directing election authorities to place the names of such candidates upon the official ballot. "Certifying officers or board" shall refer to the local election official, election authority or the State Board of Elections, as the case may be, with whom nomination papers, certificates of nomination papers and resolutions to fill vacancies in nomination are filed and whose duty it is to "certify" candidates.
10 ILCS 5/10-11