 He first won office at Quebec's Châteauguay—Huntingdon—Laprairie riding in the 1963 federal election and was re-elected in 1965, 1968, 1972 and 1974.His riding was changed to La Prairie in 1968.In the 1979 election, Watson campaigned and won in the Châteauguay riding and was re-elected there in 1980.