Barnaby Joyce has blasted Michael McCormack out to seize back his old job of Nationals leader.
Joyce's win, which automatically makes him deputy prime minister, has major implications and challenges for Scott Morrison, who had been hoping the more malleable McCormack would survive.
It was a two-horse race but, in line with its practice, the National party did not announce numbers.
Joyce is a hardliner on issues such as climate change and coal. On a very different front, he recently declared the Bileola Tamil family should be allowed return to the town.
He is a formidable retail politician and will seek to strongly differentiate the Nationals from the Liberals in the run up to the election.
He may also want to renegotiate with Morrison the detail of the Coalition agreement. He has to deal with Morrison, who is in isolation after his trip, remotely.
As Joyce takes over the Nationals in parliament, Morrison this week will be handling question time via videolink.
David Littleproud remains as deputy Nationals leader. What changes Joyce will make to the Nationals ministerial line up are yet to be revealed.
But their Senate leader, Bridget McKenzie, who was forced out of cabinet at Morrison's insistence after the sports rorts affair, appears likely to be brought back. Matt Canavan, a former resources minister, said ahead of the vote he was not seeking to return to the frontbench.
At Monday morning's Nationals party room meeting, the spill was moved by Canavan, a Joyce loyalist, and David Gillespie, a backbencher from NSW.
There had been constant criticism among Nationals of McCormack's performance, with many of them feeling he did not stand up to Morrison firmly enough.
Feeling against McCormack has intensified since the budget, when discontented Nationals believed the minor party had not received proper acknowledgement, particularly in the government's infrastructure announcements.
Some Nationals have become particularly concerned at Morrison's slow but steady move towards embracing a "net zero 2050" target. Nationals Resources Minister Keith Pitt and McKenzie both came out publicly last week declaring this was not the Nationals policy.
The Nationals were also dismayed by McCormack's embarrassing performances in parliament when acting prime minister last week.
Joyce became deputy prime minister in February 2016 after Warren Truss resigned. He quit as leader in February 2018, amid a scandal over his extra-marital affair with his now partner Vikki Campion, and a claim of sexual harassment, which he denied.
In 2017 he had to fight a byelection for his seat of New England after he was disqualified by the High Court during the dual citizenship crisis. He had been a dual New Zealand citizen and so ineligible to be a candidate at the 2016 election, the court found.
This was Joyce's second attempt to overthrow McCormack, after a failed challenge in February last year.
Asked on radio before the vote whether he was happy with McCormack's performance as Nationals leader, Morrison said, "Absolutely. I've got a wonderful partnership with Michael. We've worked very closely together and provided great, stable leadership for Australia".
McCormack said after the vote: "I've represented this nation as deputy prime minister for three years, and I'm proud of the fact I did my best, that's all you can ever ask".
Asked whether his colleagues had betrayed him, he said:"It's called democracy".
In a bizarre arrangement, Michael McCormack sat at the House of Representatives' central table, in what would normally be Morrison's chair, at question time. This was because the Governor-General is out of Canberra and so Joyce could not be sworn in immediately.
Asked by Anthony Albanese who was deputy prime minister Morrison, speaking virtually from The Lodge, said "the member for Riverina is currently the deputy prime minister of Australia".
At a news conference before question time Barnaby Joyce said he would take the issue of net zero 2050 to his party room.
He was asked whether he believed Morrison should be going to the Glasgow climate summit with a net zero by 2050 policy.
Joyce said: "I will be guided by my party room. It's not Barnaby policy - it's Nationals policy. And Nationals policy is what I will be an advocate for.
"And if the Nationals Party room believes that the best deal for regional Australia is to make sure that we secure their jobs, is to make sure we secure their industries, is to clearly understand the dynamics of an Australian economy, as opposed to a Danish one or a German one - if that's the view of the Nationals Party room, that's the view that I'll support."
Asked how he would change the Nationals Joyce said: "I have a different suite of issues. I have a different suite of attributes and I hopefully will be able to apply them in such a way as to give us the best chance [at the election]."
Joyce said he would consult his colleagues about the new Coalition agreement. A new agreement was "part and parcel of when you have a new leader," he said.
"And I'll be making sure that I talk to my colleagues in the Nationals about the issues that they see as pertinent, and I will be making sure that that respect is given to the party room."
Author: Michelle Grattan - Professorial Fellow, University of Canberra