In 1986, Deininger launched a
primary challenge against three-term incumbent Republican
John T. Manske for his seat in the
Wisconsin State Assembly. The district at the time was composed of parts of
Green County, of which Deininger was a resident, and
Rock County, where Manske resided. In the 1984 election, Deininger had worked for Manske's re-election campaign, but declared in 1986 that it was "Green County's turn to be represented in the Assembly." Deininger won a surprising upset in the September primary and was then unopposed in the general election. He was re-elected in 1988, and 1990, and after
redistricting in 1991, was elected to another term in 1992. In 1994, he ran unopposed for election to the
Wisconsin Circuit Court in Green County, and resigned from the Wisconsin Assembly.
Government Accountability Board In 2008, Deininger was appointed to the
Wisconsin Government Accountability Board (GAB), by Governor
Jim Doyle, and served as the GAB's first chairman. The Attorney General found that even though Deininger had retired from the Court of Appeals, he was ineligible to serve on the GAB because the term he was elected to had not expired. Following the Attorney General's finding, Deininer resigned from the Board. ==After retirement==