Warschauer Vertrag
On the same day, Brandt signed the Treaty of Warsaw, which acknowledged the Oder–Neisse line as the final German border with Poland. Both actions attracted controversy within Germany, as did Ostpolitik in general, which was supported by only a narrow majority of the people and had opposition within Brandt's own Social Democratic Party. Its voters had included a significant proportion of expellees from the formerly-German territories in Poland, most of whom left to support the conservative parties.