He was a Labor politician in Tasmania from 1909 until 1929 and was Premier there from 1923 until 1928. He became a federal politician in 1929. When the Labor Party split in 1931, Lyons and others left, joining with the Nationalists to form the United Australia Party. Lyons led the Opposition from 1931 until 1932, when he became Prime Minister (1932–39), embarking on a programme of rearmament.