10 ILCS 5/23-20
The person desiring to contest such election shall, within thirty (30) days after the person whose election is contested is declared elected, file with the clerk of the proper court a petition, in writing, setting forth the points on which he will contest the election, which petition shall be verified by affidavit in the same manner as complaints in other civil cases may be verified. Copies of such petition shall be delivered by mail to each proper clerk or board of election commissioners who is a custodian of any ballots involved in the contest. The petition shall allege that the petitioner voted at the election, and that he believes that a mistake or fraud has been committed in specified precincts in the counting or return of the votes for the office or proposition involved or that there was some other specified irregularity in the conduct of the election in such precincts, and the prayer of the petition shall specify the precincts in which the recount is desired.
10 ILCS 5/23-20