Even before his election as Chancellor, Willy Brandt, the Social Democratic mayor of West Berlin, argued for and pursued policies that would ease tensions between the two German states, generally in the interest of cross-border commerce. His proposed new Ostpolitik held that the Hallstein Doctrine did not help to undermine the communist regime or even lighten the situation of the Germans in the GDR. Brandt believed that collaboration with the communists would foster German-German encounters and trade that would undermine the communist government over the long term.