Torp was President of the workers ' Party of Norway from 1923 to 1945 and was Mayor of Oslo in 1934-1935. In 1936 he became Minister of defence in the Government of Johan Nygaardsvold. Thereafter he was still Minister of Social Affairs (1936-1939), of Finance (1939-1942), again by Öandsverdediging (1942-1975) and of transport (1945-1948). In 1951 he became Prime Minister. Afterwards he became President of the Deposit (1955-1958).