CANBERRA, Australia — Prime Minister Malcolm Turnbull of Australia lost the support of his own party on Thursday, setting up a race between two challengers — one a conservative rival, the other a moderate ally — to take the reins of leadership.
The governing Liberal Party’s infighting made a confused week even more chaotic. At noon on Thursday, the House of Representatives, Parliament’s lower house, voted to adjourn until Sept. 10. An hour later, Mr. Turnbull told reporters he would hold a party vote on Friday if he received a letter from lawmakers with enough signatures showing support for the challenge.
Calling it an “internal insurgency,” Mr. Turnbull said he would resign from Parliament if he was deposed.
“The public hate what is going on at the moment,” he said, referring to Australia’s revolving door of leadership, in which seven prime ministers have been named in the past 11 years. “They want everyone here to be focused on them.”
Mr. Turnbull, a moderate and former investment banker, is now largely seen as too weak to survive. The questions now: Who will replace him? And when?
“The leadership churn is unprecedented. No prime minister since John Howard, who lost office in 2007, has served a full term in office,” said Michael Fullilove, executive director of the Lowy Institute, a nonpartisan think tank. “Governments seem incapable of exercising their authority. They spend most of their time in survival mode.”
The day started with three senior cabinet ministers informing Mr. Turnbull that he no longer had their support and must hold an internal ballot for prime minister, the second such party vote this week.
By late morning, Mr. Turnbull faced challenges from Peter Dutton, a conservative who served as home affairs minister under Mr. Turnbull, and Scott Morrison, the treasurer, who pledged his loyalty to Mr. Turnbull as recently as Wednesday.
By midday, the House found itself in the remarkable position of debating adjournment, abandoning debate on issues like the country’s punishing drought, to allow for the leadership fight to play out.
The opposition Labor Party pounced.
“The Liberal Party today has no interest in anyone but themselves,” said Tony Burke, a Labor lawmaker, as the adjournment motion was being debated. “They have completely fallen apart, collapsed.”
“What a legacy,” another lawmaker shouted on the floor of the House.
For Mr. Dutton, 47, the conservative former police officer who mounted a first challenge after a dispute over a modest proposal to cut emissions, the day began with conflict. Under gray clouds at an 8 a.m. news conference, Mr. Dutton announced a second challenge.
A handful of ministers resigned soon after and withdrew their support from Mr. Turnbull, including a key power broker, Mathias Cormann, the finance minister and a senior figure in the Turnbull cabinet.
Mr. Cormann made clear before lunchtime that the leadership would need to change. “We’ve made a judgment that in our view there is a majority support in the party room for change,” he said.
It was then that Mr. Morrison said he, too, would be a candidate to be the Liberal Party’s leader.
That has set up the current standoff between the Liberal Party’s moderate and conservative wings, and a scramble for support. Outside the prime minister’s chambers, reporters gathered to see who went in and who came out, tracking the length of their discussions and demeanor.
The chances of success for Mr. Dutton, whose rise had seemed inevitable Wednesday night, seemed to weaken with every hour.
Earlier in the day, he tried to tamp down questions about his family’s ownership of two child-care centers, which had received government subsidies — a potential violation of the Constitution.
Under Section 44 of the Constitution, “any direct or indirect pecuniary interest with the Public Service of the Commonwealth” makes a person disqualified from sitting in Parliament.
Mr. Dutton called the allegations, first reported by Ten Daily, “spurious and baseless” and said he had not breached the Constitution, but the case added a cloud of doubt to his candidacy.
Mr. Turnbull said he would wait to call for a party vote in order for the legality of Mr. Dutton’s position in Parliament to be resolved.
“This issue of eligibility is critically important,” he said. “You can imagine the consequences of having a prime minister whose actions and decisions are questionable because of the issues of eligibility.”
Experts said the move to delay could help Mr. Morrison rally support.
“Peter Dutton is so far on the right within the Liberal Party that there will be conservatives who would not relish voting for him,” said Jill Sheppard, a lecturer at the Australian National University. “For these people, Scott Morrison presents an acceptable alternative. He has conservative credentials but he’s much closer to the center.”
Mr. Morrison, 50, has long played in the middle of Australian politics. Representing Cook, in New South Wales, he presented himself as a moderate in his first speech to Parliament in 2007, and while he has most recently served as treasurer, he has played a variety of roles in government.
Experts said he had the capacity to rally support from both moderates and conservatives, but it was not clear if he would succeed for one reason: He is close to Mr. Turnbull and may not represent enough of a change.