In July 1986, Miller was elected as First Secretary of the PZPR Provincial Committee in Skierniewice. In December 1988, he returned to Warsaw, due to his promotion to the position of the Secretary of the PZPR Central Committee. As a representative of the government side, he took part in the session of the historic "Round Table", where, together with Andrzej Celiński, he co-chaired the sub-team for youth issues (the only one that closed the session without signing the agreement). In 1989, he became a member of the PZPR Political Bureau.