In 1973 Gaus made an abrupt switch to a form of politics, accepting a post as Secretary of state in the Chancellor's Office. The chancellor's intention was that Gaus should take on a quasi-diplomatic role in respect of the intensively political issues surrounding Intra-German relations. Everything involved in relations between West Germany and East Germany was complicated by the fact that legally - and in the eyes of conservatives on both sides of the divide, politically - there was no mutual recognition between the two "states". There could be no question of appointing an ambassador or even a conventional "chargé d'affaires" to a country that did not, under West German law, exist as a separate entity. Contemporary and subsequent sources tend to describe the posting as something along the lines "the first head of the permanent representation of the Federal Republic of Germany in the German Democratic Republic". Appropriate changes to the (West) German constitutional "Basic law", following laborious negotiations, entered into legal force for most purposes at the end of 1973. On 2 May 1974 West Germany's opened at Hannoversche Straße 28–30 in East Berlin under the direction of Günter Gaus. He retained the posting till 1981, despite the resignation from the chancellorship of Willy Brandt at around the same time as the mission was opened. Gaus' relationship with Brandt's successor as chancellor, Helmut Schmidt, was never a particularly easy one.