On 17 March 2018, Xenophon unsuccessfully contested the seat of Hartley in the South Australian House of Assembly at the 2018 South Australian state election. Although he came second on the primary vote ahead of Labor's Grace Portolesi by 202 votes, upon the preference distribution of the eliminated fourth-placed Greens candidate, Xenophon's 99 vote lead over Labor became a 357-vote deficit. Third-placed Xenophon was therefore eliminated, with Hartley reverting to the traditional Liberal vs Labor contest.
