In 1969 his party formed a new coalition with the Social Democrats. He became Foreign Minister and Vice Chancellor. With Willy Brandt his foreign policy meant the Federal Republic of Germany promised not to try and get back the parts of Germany given to Poland and the USSR. The treaty with Poland actually defined the western border of Poland, not the border between Poland and Germany. It is the same thing, but meant Poland could sign a treaty with West Germany that described the border of East Germany.
When Brandt resigned on 7 May 1974, Scheel, was acting chancellor, for about a week, until Helmut Schmidt was elected Chancellor.
Like most ex German presidents, Scheel retired from political life term ended. He did sometimes appears on political talk shows or events. At the funeral of the murdered businessman Hanns Martin Schleyer in October 1977, Scheel gave a speech entitled shame.