10 ILCS 5/23-13
The contestant shall, within 30 days after the proclamation of the result of the canvass of the State electoral board as provided in Section 22-7, serve a notice of his intention to contest such election, expressing the points on which the same will be contested; and shall deliver a copy of such notice to each proper clerk or board of election commissioners, as the case may be, who is a custodian of any ballots involved in the contest and to the State Board of Elections. If the contest is of the election of senator from a legislative district, such notice shall be served on the person declared to be elected to the Senate from that district. If the contest is of the election of a representative or representatives from a legislative district, such notice shall be served on each person declared to be elected to the House of Representatives from that district. In case any person whose election is contested is absent, or cannot be found, service may be had by leaving a copy of such notice at his usual place of residence. Nothing herein shall be construed to abridge the authority of either house of the General Assembly to judge the elections, returns and qualifications of its members in any manner determined by that house.
10 ILCS 5/23-13