The voters of Canning could have quite a say on Tony Abbott's leadership

So once again Tony Abbott has told the Coalition party room that he’s ticked off his cabinet ministers. Read them the riot act, he said.

They seem to be slow learners, those ministers. Or, more to the point, some of them are increasingly angry with their leader. It was only June when Abbott lectured them about leaking and said later there had been a “come to Jesus moment” in cabinet. The moment quickly passed, apparently.

Abbott now is frustrated by both leaks and ministers speaking out publicly about the way forward on same-sex marriage. But at Monday’s cabinet he failed to finalise a process, beyond confirming the popular vote would be next term, not before.

Crucially, there is no decision on whether that vote would be a plebiscite or referendum. Abbott is bringing something back to cabinet and the party room. The majority thinking in cabinet seems for a plebiscite; if he proposed a referendum, he might need to get out the tear gas.

Amid reports of leadership chatter - going nowhere at the moment - a serious crisis over the position of royal commissioner Dyson Heydon, and mounting fear on the backbench came Tuesday’s Newspoll taken in the byelection seat of Canning in Western Australia. It showed a 10% swing against the government in an electorate it holds with an 11.8% margin. The Liberal-Labor two-party vote in the poll was 51-49%.

If Canning were lost on September 19, or even run very close, Abbott’s grip on the leadership would become quite tenuous, with pressure potentially coming on him to consider a walk in the snow for the good of the party.

But the byelection is also a test for Labor, so if the swing were modest, Abbott would get protection and attention would come back on Bill Shorten.

In between, say a swing of around 8%, would be open to “spin” from winner and loser.

At present the predictions on both sides are that the government will narrowly retain the seat.

The spinning is already starting in an attempt to manage expectations. The government argues that former member Don Randall, whose death precipitated the byelection, had a very strong personal following – highlighted when lower house and Senate votes in individual WA seats are compared.

Labor counters by noting that when an MP dies, the swing is less than in contests triggered by a resignation, which is often accompanied by anger over the circumstances.

Figures prepared by the Parliamentary Library of two-party swings against governments at byelections between 1949 and 2014 show an average of 4% for all seats (5% in government-held seats). At byelections following resignations the average swing against governments was 4.9%; it has been only 2.5% where the vacancy was caused by a death.

But averages mask some important individual cases, because byelections can be politically defining. When, after the death of the Liberal member, John Howard held Aston in 2001, with an anti-government swing of 3.7%, it was a significant step in his recovery from the dramatic low that had seen him written off by many of his own.

The last time a seat changed hands after a death was in 1966 - Labor seized the Queensland regional electorate of Dawson from the Country party. This was an early demonstration of the campaigning skills of Gough Whitlam, who was deputy leader of the ALP.

If Shorten wants a benchmark, he might note that the swing in Dawson was 11.9%.

Canning, which divides into distinct geographic sections, stretches from south east Perth to the regional centre of Mandurah, about 70 kilometres from Perth and the second largest city in Western Australia. Its make up is variously described by the parties as including tradies, lower middle class voters, “aspirational Australians”, and retirees.

The voters' concerns will include the basics of jobs and cost of living. The Liberals will attempt to make the contest as local as possible – about who is the best candidate to follow Randall. Labor will try to exploit the unpopularity of the federal government and Abbott, and the feeling against the Barnett state government.

The Liberals have been quick out with a candidate - a 32-year-old SAS captain, Andrew Hastie, who has served in Afghanistan. The party will be anxious to broaden his image beyond that of the elite soldier.

Labor appears to have been caught rather off guard, thinking the election might be in October; its candidate will be selected at the weekend. The frontrunner is a lawyer, Matt Keogh, but there is also interest in Kelly McManus, a one time staffer of Kim Beazley, who works in Mandurah. Labor’s vote there was low last time, so she could be well placed to maximise the pick up in that area.

Abbott will be in Perth on Friday and Saturday, to address the Liberal state council and do some campaigning. For most of the coming weeks, however, he will be either on his annual stint in an indigenous community or in Canberra for parliament. He’ll obviously return to Canning but the electors are unlikely to see much of him. It wouldn’t be the first occasion that a strategic absence is seen as his best approach.

For both the Greens and Clive Palmer, the byelection will be important. It will be Richard Di Natale’s first test as leader. Palmer’s party triumphed in the WA re-run Senate election, but since then has effectively collapsed, with Dio Wang, from WA, its only senator, down from its original three. The byelection will test whether PUP has disappeared from the radar altogether.

The voters of Canning will feel the political love or, more likely, be driven mad by it. The focus groups and polling will be intense; the spending will be huge, especially by the Liberals, given the stakes.

The mood of Canning could help determine whether Abbott’s colleagues have a “come to Jesus moment” - defined by Prime Minister’s Office in June as a moment of collective clarity – in their view about their futures and his.

Listen to the latest Politics with Michelle Grattan podcast with guest, Clare O'Neil, talking about her new book Two Futures.