Prime Minister of Australia prime minister, otherwise William McMahon63. Robert Menzies was the oldest person to ever be prime minister, leaving office at 71 years old. The longest-serving Prime Minister was Sir Robert Menzies, who served in office twice: from 26 April 1939 to 28 August 1941, and again from 19 December 1949 to 26 January 1966. In total Robert Menzies spent 18 years, 5 months and 12 days in office. He served under the United Australia Party and the Liberal Party respectively. The shortest-serving Prime Minister was Frank Forde, who was appointed to the position on 6 July 1945 after the death of
History of the Australian Labor Party the party until the loss at the 1977 election, when he was succeeded by Bill Hayden. Whitlam retired from parliament in 1978. Hayden increased the Labor vote at the 1980 election. He was replaced by Bob Hawke in 1983, who led Labor back to office at the 1983 election. Hawke was defeated as Labor leader in a 1991 spill by Paul Keating, who had been Treasurer of Australia since 1983. Hawke is Labor's longest-serving Prime Minister and Australia's third-longest-serving Prime Minister. Hawke retired from parliament in 1992. Hawke and Keating led Labor to victory at five consecutive federal elections: 1983,