From 1955 to 1973, he also was a member of the precursors to the European Parliament, first of the Common Assembly of the European Coal and Steel Community (1955–1958) and then of the European Parliamentary Assembly of the European Communities (1958–1973). He served as president of these bodies from 1956 to 1958 and from 1960 to 1962 and as vice president from 1962 to 1973.