After setting up Saskatchewan's universal healthcare program, Douglas stepped down and ran to lead the newly formed federal New Democratic Party (NDP), the successor party of the national CCF. He was elected as its first federal leader in 1961. Although Douglas never led the party to government, through much of his tenure the party held the balance of power in the House of Commons. He was noted as being the main opposition to the imposition of the "War Measures Act" during the 1970 October Crisis. He resigned as leader the next year, but remained as a Member of Parliament until 1979.