Republican David Olsen will fill former state Rep. Ron Sandack's (R-Downers Grove) seat in the Illinois House.
Sandack suddenly resigned last week in light of recent "cyber security issues" he faced.
Chairmen of the DuPage and Will County Republican Parties selected Olsen, from Downers Grove, as Sandack's replacement on Saturday.
Olsen, 27, is vice chairman of the College of DuPage board and also serves as a Downers Grove village commissioner and chairman of the Downers Grove Township Republican Organization.
Olsen, who will serve out Sandack's remaining term and run for the seat in the November election, is expected to be sworn in Wednesday. He plans to step down from the Downers Grove village council.