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 and other pro-conscriptionists to split off as the National Labor Party, which after a few months merged with the Commonwealth Liberal Party to form the Nationalist Party. 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 in the Australian parliament since federation. Meanwhile, the ALP suffered a large swing against it, losing almost seven percent of its vote from 1914.
House of Reps 1917–19 (FPTP) — Turnout 78.30% (Non-CV) — Informal 2.64%