After the German reunification in 1990, Thuringia became a state of Germany. Lieberknecht held many offices in the state: Minister of Education from 1990 to 1992; Minister of Federal and European Affairs from 1992 to 1999; President of the Landtag of Thuringia from 1999 to 2004; leader of the CDU parliamentary group in the Landtag of Thuringia from 2004 to 2008 and Minister of Social Affairs from 2008 to 2009.