10 ILCS 5/7-61
Whenever a special election is necessary, the provisions of this Article are applicable to the nomination of candidates to be voted for at such special election.
In cases where a primary election is required, the officer or board or commission whose duty it is under the provisions of this Code relating to general elections to call an election shall fix a date for the primary for the nomination of candidates to be voted for at such special election. Notice of such primary shall be given at least 15 days prior to the maximum time provided for the filing of petitions for such a primary as provided in Section 7-12.
Any vacancy in nomination under the provisions of this Article 7 occurring on or after the primary and prior to certification of candidates by the certifying board or officer must be filled prior to the date of certification. Any vacancy in nomination occurring after certification but prior to 15 days before the general election shall be filled within 8 days after the event creating the vacancy. The resolution filling the 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 resolution shall be deemed filed within such 3-day limit. Failure to so transmit the 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 officers of a local municipal or township political party as specified in subsection (h) of Section 7-8, other than a statewide political party, that is established only within a municipality or township and the managing committee (or legislative committee in case of a candidate for State Senator or representative committee in the case of a candidate for State Representative in the General Assembly or State central committee in the case of a candidate for statewide office, including, but not limited to, the office of United States Senator) of the respective political party for the territorial area in which such vacancy occurs.
The resolution to fill a vacancy in nomination shall be duly acknowledged before an officer qualified to take acknowledgments 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 7-10, 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 Section 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 the consolidated election or the general 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 general election.
A vacancy in nomination occurs when a candidate who has been nominated under the provisions of this Article 7 dies before the election (whether death occurs prior to, on or after the day of the primary), or declines the nomination; provided that nominations may become vacant for other reasons.
If the name of no established political party candidate was printed on the consolidated primary ballot for a particular office and if no person was nominated as a write-in candidate for such office, a vacancy in nomination shall be created which may be filled in accordance with the requirements of this Section. Except as otherwise provided in this Code, if the name of no established political party candidate was printed on the general primary ballot for an office nominated under this Article and if no person was nominated as a write-in candidate for such office, a vacancy in nomination shall be filled only by a person designated by the appropriate committee of the political party and only if that designated person files nominating petitions with the number of signatures required for an established party candidate for that office within 75 days after the day of the general primary. The circulation period for those petitions begins on the day the appropriate committee designates that person. The person shall file his or her nominating petitions, statements of candidacy, notice of appointment by the appropriate committee, and receipt of filing his or her statement of economic interests together. These documents shall be filed at the same location as provided in Section 7-12. The electoral boards having jurisdiction under Section 10-9 to hear and pass upon objections to nominating petitions also shall hear and pass upon objections to nomination petitions filed by candidates under this paragraph.
A candidate for whom a nomination paper has been filed as a partisan candidate at a primary election, and who is defeated for his or her nomination at such primary election, is ineligible to be listed on the ballot at that general or consolidated election as a candidate of another political party.
A candidate seeking election to an office for which candidates of political parties are nominated by caucus who is a participant in the caucus and who is defeated for his or her nomination at such caucus is ineligible to be listed on the ballot at that general or consolidated election as a candidate of another political party.
In the proceedings to nominate a candidate to fill a vacancy or to fill a vacancy in the nomination, each precinct, township, ward, county, or congressional district, as the case may be, shall, through its representative on such central or managing committee, be entitled to one vote for each ballot voted in such precinct, township, ward, county, or congressional district, as the case may be, by the primary electors of its party at the primary election immediately preceding the meeting at which such vacancy is to be filled.
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, the election authority, or the State Board of Elections, as the case may be, with whom nomination papers, including certificates of nomination and resolutions to fill vacancies in nomination, are filed and whose duty it is to certify candidates.
10 ILCS 5/7-61