The Coalition’s grasp on the West Australian federal seat of Canning appears to have slipped further just a month before a byelection there.

Liberal MP Don Randall, who died of a heart attack in July, had a lead of almost 12%, but the latest Newspoll shows that margin has all but disappeared.

The poll, which surveyed 508 Canning voters last weekend and was published by the Australian, shows the government ahead by 51% to 49% in two-party-preferred terms. At the last federal election in 2013 it won with 61.8% to Labor’s 38.2%.



Opposition Leader Bill Shorten told the Labor caucus last week that by-elections in seats in which an MP had died tended to swing away from the former member’s party by only about 2.5%, but that the party would still take up the fight in Canning.

On Monday Speaker Tony Smith issued the writ for the byelection, which will be held on 19 September.

SAS soldier Andrew Hastie is all but confirmed as the Liberal candidate, with the prime minister, Tony Abbott, expected to launch his campaign at the party’s state conference on Saturday. Hastie, 32, was recommended by the party’s selection committee as the best of seven candidates and has the backing of senior Liberals including the finance minister, Mathias Cormann, and the foreign minister, Julie Bishop.

He emerged as the lead candidate last week, overtaking Randall’s daughter, Tess Randall.

Labor’s list of potential candidates is headed by Matthew Keogh, the president of the Law Society of WA and one-time policy adviser to former Labor premier Geoff Gallop. Nominations for ALP preselection close on Thursday and will be put to the vote by local electors at the weekend.

The Palmer United party and the Greens are also expected to stand candidates.