 In 1991, he advocated for Northern Illinois University to convert the Campbell Center in Mount Carroll, Illinois into a regional branch, similar to ones in Hoffman Estates and Naperville.In 1992, he was elected to the Illinois Senate to represent the 37th district to succeed Calvin W. Schuneman.After the 2001 redistricting, Sieben's district was renumbered to the 45th and drawn to include all of Jo Daviess, Stephenson and Lee counties and portions of Winnebago, Ogle, Carroll, Whiteside and Henry counties.