Krichbaum was always directly elected as a representative of the constituency Pforzheim in the Bundestag. In his first election in 2002, he was able to regain for the CDU the direct mandate lost in 1998 to the SPD against the state leader of the SPD Baden-Württemberg, Ute Vogt. He defended this in 2005 with 46.9% and in 2009 with 40.7% of the first votes. In the general election in 2013, he reached with 49.5% of the first votes the best result of the CDU in this constituency since the federal election in 1983. In his fifth federal elections 2017, he could not repeat this result, but won the direct mandate with 36.4% of the votes.