Hughes, then a member of the ALP, had become Prime Minister when Andrew Fisher retired in 1915. The ALP split on conscription had led Hughes 24 and other pro-conscription Labor MPs to split off as the National Labor Party, which was able to form a minority government supported by the Commonwealth Liberal Party, led by Joseph Cook. Later that year, National Labor and the Liberals merged to form the Nationalist Party, with Hughes as leader and Cook as deputy leader. The election was fought in the aftermath of the 1916 plebiscite on Conscription in Australia, which had been narrowly defeated. The Nationalists won a decisive victory, securing the largest majority government since Federation. Meanwhile, the ALP suffered a large swing against it, losing almost seven percent of its vote from 1914. The swing was magnified by the large number of former Labor MPs who followed Hughes out of the party.
House of Reps 1917–19 (FPTP) — Turnout 78.30% (Non-CV) — Informal 2.64%