Haga served as State Secretary for Foreign Affairs from 1991 – 1997 and Minister of Culture from 1999 to 2000. In 2001, she was elected to the Storting from Akershus County, and she was re-elected in 2005. In 2003, while the Centre Party was an opposition party, she became party leader. As leader of the Centre Party, Haga was instrumental in swinging the party's political course to the left, bringing it into a coalition with the Labour Party and the Socialist Left Party for the first time.