10 ILCS 5/25-6
2021 Illinois Compiled Statutes|Chapter 10 - ELECTIONS|10 ILCS 5/ - Election Code.|Article 25 - Resignations And Vacancies

 (from Ch. 46, par. 25-6)Sec. 25-6. General Assembly vacancies.(a) When a vacancy occurs in the office of State Senator or  Representative in the General Assembly, the vacancy shall be filled within  30 days by appointment of the legislative or representative committee of  that legislative or representative district of the political  party of which the incumbent was a candidate at the time of his  election. Prior to holding a meeting to fill the vacancy, the committee shall make public (i) the names of the committeeperson on the appropriate legislative or representative committee, (ii) the date, time, and location of the meeting to fill the vacancy, and (iii) any information on how to apply or submit a name for consideration as the appointee. A meeting to fill a vacancy in office shall be held in the district or virtually, and any meeting shall be accessible to the public. The appointee shall be a member of the same political party as  the person he succeeds was at the time of his election, and shall be  otherwise eligible to serve as a member of the General Assembly.(b) When a vacancy occurs in the office of a legislator elected  other than as a candidate of a political party, the vacancy shall be  filled within 30 days of such occurrence by appointment of the Governor.  The appointee shall not be a member of a political party, and shall be  otherwise eligible to serve as a member of the General Assembly.  Provided, however, the appropriate body of the General Assembly may, by  resolution, allow a legislator elected other than as a candidate of a  political party to affiliate with a political party for his term of  office in the General Assembly. A vacancy occurring in the office of any  such legislator who affiliates with a political party pursuant to  resolution shall be filled within 30 days of such occurrence by  appointment of the appropriate legislative or representative  committee of that legislative or representative district of the political  party with which the legislator so affiliates. The appointee shall be a  member of the political party with which the incumbent affiliated.(c) For purposes of this Section, a person is a member of a  political party for 23 months after (i) signing a candidate petition, as  to the political party whose nomination is sought; (ii) signing a  statement of candidacy, as to the political party where nomination or  election is sought; (iii) signing a Petition of Political Party  Formation, as to the proposed political party; (iv) applying for and  receiving a primary ballot, as to the political party whose ballot is  received; or (v) becoming a candidate for election to or accepting  appointment to the office of ward, township, precinct or state central committeeperson.(d) In making appointments under this Section, each committeeperson of  the appropriate legislative or representative committee  shall be entitled to one vote for each vote that was received, in that  portion of the legislative or representative district which he represents  on the committee, by the Senator or Representative whose seat is vacant at the  general election at which that legislator was elected to the seat which  has been vacated and a majority of the total number of votes received in  such election by the Senator or Representative whose seat is vacant is  required for the appointment of his successor; provided,  however, that in making appointments in legislative or representative  districts comprising only one county or part of a county  other than a county containing 2,000,000 or more inhabitants, each committeeperson   shall be entitled to cast only one vote.(e) Appointments made under this Section shall be in writing  and shall be signed by members of the legislative or representative committee  whose total votes are sufficient to make the appointments or by the  Governor, as the case may be. Such appointments shall be filed with the  Secretary of State and with the Clerk of the House of Representatives or  the Secretary of the Senate, whichever is appropriate.(f) An appointment made under this Section shall be for the  remainder of the term, except that, if the appointment is to fill a  vacancy in the office of State Senator and the vacancy occurs with more  than 28 months remaining in the term, the term of the  appointment shall expire at the time of  the next general election at which time a  Senator shall be elected for a new term commencing on the determination  of the results of the election and ending on the second Wednesday of  January in the second odd-numbered year next occurring.  Whenever a  Senator has been appointed to fill a vacancy and  was thereafter elected to that office, the term of service under the  authority of the election shall  be considered a new term of service, separate from the term of service  rendered under the authority of the appointment.  (Source: P.A. 102-15, eff. 6-17-21.)