With the British Expeditionary Force in retreat to Dunkirk and the fall of France seemingly imminent, Halifax believed that the government should explore the possibility of a negotiated peace settlement. His hope was that Hitler's ally, the still-neutral Italian dictator Mussolini, would broker an agreement. When a memorandum proposing this approach was discussed at the War Cabinet on 27 May, Churchill opposed it and urged his colleagues to fight on without negotiations. He was supported in the war cabinet by its two Labour Party members, Clement Attlee and Arthur Greenwood, and also by the Secretary of State for Air, Sir Archibald Sinclair, who as leader of the Liberal Party was co-opted to the war cabinet for its meetings about the proposed negotiations. Churchill's biggest problem was that he was not the leader of the Conservative Party and he needed to win the support of ex-Prime Minister Neville Chamberlain, without which he could have been forced to resign by the large Conservative majority in the House of Commons.