WHEN it looked as if he might hold on to his job, Malcolm Turnbull, Australia’s prime minister, insisted that for his fellow Liberal MPs, the bedrock of the governing coalition, “Unity is critical.” At that point, on August 21st, he had just precipitated and survived a vote on his own leadership. But the challenger he wrong-footed, Peter Dutton, the home-affairs minister (pictured standing), refused to give up. He began circulating a petition for another vote within the Liberal caucus, and persuaded a series of allies to resign as ministers. When it became clear that his support was crumbling, Mr Turnbull changed tone.

“I’ve never given in to bullies,” the prime minister declared at a press conference, while appearing to give in. He said he would resign if Mr Dutton produced a petition from a majority of Liberal MPs asking for a fresh vote—something Mr Dutton should be able to do, given all the resignations from the cabinet. But Mr Turnbull laid several traps for Mr Dutton even as he conceded. First, he delayed the vote on the next leader until August 24th, giving potential rivals to Mr Dutton a little time to rally support. Second, he asked the solicitor-general for an opinion about whether Mr Dutton might be ineligible to serve in parliament, given that his family trust has interests in child-care centres that receive government subsidies. That could put him in breach of a constitutional ban on MPs profiting from the government they oversee. Third, Mr Turnbull said he would resign from parliament if the leadership challenge went ahead, prompting a by-election in his marginal seat. Since the government has a majority of one in the lower house (and a minority in the Senate), the new prime minister may not last long.

As The Economist went to press, Mr Turnbull seemed clearly on the way out. Mr Dutton may well prevail over the other candidates, Julie Bishop, the foreign minister, and Scott Morrison, the treasurer. For the fourth time in less than a decade, government MPs are turfing out a prime minister in search of electoral advantage.

The previous beneficiary of such a coup was Mr Turnbull himself, who unseated Tony Abbott as prime minister and Liberal leader in 2015. The opposition Labor party has also indulged in “spill motions”, as the leadership votes are known, first evicting Kevin Rudd in 2010 in favour of Julia Gillard and then reinstating him in 2013. That did not stop Labor denouncing the current upheaval as a shameful shambles and a betrayal of the people’s trust. On past precedent, the people are likely to see it that way too. None of the three previous changes of prime minister revived the electoral fortunes of the ruling party.

That raises the question of why Liberal MPs are so busily writing a political “suicide note”, as one of them put it. Personal grievances play a part. Mr Dutton’s support comes from a hard-right faction within the Liberal caucus. Their leading light is the vengeful Mr Abbott, who thinks Mr Turnbull has dragged the party too far to the left. Mr Abbott and his allies want more restrictions on immigration and fewer on burning coal. Given the government’s minuscule majority, his small band of rebels has been able to stymie the prime minister’s legislative agenda.

The rebels have grown louder as successive polls have shown that the Liberal-led coalition is likely to lose the next election, due by May. The latest flashpoint was the government’s unambitious proposal to trim greenhouse-gas emissions, in keeping with cuts that Mr Abbott himself approved by signing the Paris agreement on climate change. The insurrection forced Mr Turnbull to abandon the targets.

Mr Turnbull has proved a disappointing leader. He painted himself as a principled reformer, but has spent more time appeasing right-wing critics than fighting for his beliefs. By backtracking on climate change, an issue about which he professes to be passionate, he showed himself willing to jettison even his dearest policies.

Good cop or bad cop?

Yet Mr Dutton, an ex-policeman, is an unlikely alternative. As the minister most recently responsible for incarcerating asylum-seekers in foreign processing centres, he has positioned himself as one of his party’s most reactionary figures. He blames black Africans for inciting gang violence, and wants to offer white South African farmers a special category of humanitarian visa. When the prime minister of the day, Kevin Rudd, apologised ten years ago to the “stolen generation” of aboriginal children forcibly removed from their families, Mr Dutton walked out of parliament in disgust.

Australians are frustrated by stagnant wages, but they have never rallied behind right-wing populists. Polls suggest Mr Dutton is either disliked by or unknown to voters. His main appeal is tribal: he hails from Queensland, whose swing seats could determine the outcome of the election. A humiliating defeat in a by-election there last month sent Liberals into a frenzy. Mr Dutton’s backers hope that his stance on immigration might win back some votes.

Yet even if they are right, the fad for spill motions makes Australian politics look alarmingly unstable. Not one prime minister has completed a three-year term since John Howard, another conservative, lost power in 2007. The new one is unlikely to buck that trend.