He became a founder of and full-time organiser for the People's Front Propaganda Committee, which aimed to unite members of all parties against fascism and the British government's indifference to or appeasement of it. He spoke in favour of this policy at Labour's 1939 conference, but was heavily defeated, and the committee soon dissolved. The Second World War broke out shortly afterwards, and Murphy returned to work as a turner, also becoming a shop steward again for the AEU. He argued in favour of the Hitler–Stalin pact on the grounds that, he believed, Stalin had no choice in order to buy time.