Australian by-election a litmus test for right-wing One Nation Party

Polls have opened in a key by-election in regional Australia, viewed as an electoral test of support for the right-wing populist One Nation Party, which could win its first federal lower house race.The contest in Farrer, a vast regional electorate in New South Wales, was triggered by the resignation of Sussan Ley, who quit when she was ousted as the opposition conservative Liberal Party leader after nine months.While the Liberals are running a candidate to replace Ley, opinion polls suggest it could be a close contest between local independent Michelle Milthorpe and One Nation's David Farley.Voting booths close at 18:00 local time (09:00 BST) on Saturday, with results expected shortly after.Milthorpe, a local teacher, came second in the two-candidate preferred count at last year's federal election against Ley, who recorded her worst result as a sitting MP since she first won the seat in 2001.Australia has a preferential voting system where voters rank candidates from their most to least preferred. The final tally is calculated as a challenge between two candidates after preferences are distributed, known as the two-candidate preferred count.While the by-election result will not affect the Labor government's massive majority, it could see the first One Nation MP elected to Australia's national parliament.Saturday's poll is the first federal test of One Nation's support after the party recorded the second-highest number of votes out of any political party in the South Australian state election in March – its best ever electoral performance.