After the federal and regional elections of June 1999 in which, due to the Dioxin Affair, the Christian-Democrats lost many of their votes, Di Rupo negotiated with the Flemish socialists of sp.a, the Liberals and Green Party to form a "purple-green" government. Di Rupo himself was in charge of the function of minister-president of the Walloon region, but already in October of the same year the members of the party chose him as president and in April 2000, he was succeeded in his function of minister-president by Jean-Claude Van Cauwenberghe.