From 1976 to 2017, he served as a member of the federal German legislature, the Bundestag. At first he was elected via the "Landesliste" ("state list"), then from 1980 he represented the electoral district Frankfurt am Main I - Main-Taunus and since 2002 the district Main-Taunus. This period of over 40 years has made him the third-longest member, after Wolfgang Schäuble and Richard Stücklen. In the elections of 2009 he attained 47,5 % of the votes, in 2013 52,5 %.