Senior ministers deal death blow to Malcolm Turnbull's prime ministership

Malcolm Turnbull has been delivered a political death blow, with the resignation of three senior cabinet ministers – Mathias Cormann, Michaelia Cash and Mitch Fifield.

They said in a joint news conference shortly before 10 am that they had advised Turnbull on Wednesday and again Thursday morning that he no longer had party support.

Senate leader Cormann, whose position has always been considered crucial in the leadership battle, said he had been told by five cabinet ministers who had voted for Turnbull on Tuesday that he no longer had their support.

“It’s with great sadness and a heavy heart that we went to see the Prime Minister yesterday afternoon to advise him that in our judgment he no longer enjoyed the support of the majority of members in the Liberal Party party room and that it was in the best interests of the Liberal Party to help manage an orderly transition to a new leader.

"I can’t ignore reality”, Cormann said, who on Tuesday pledged continuing support to Turnbull in comments to the Senate.

A party meeting is now inevitable. The crucial question is whether Turnbull stands aside to open the way for Treasurer Scott Morrison and deputy Liberal leader Julie Bishop to possibly run.

Early Thursday morning, Peter Dutton demanded Turnbull hold a second leadership vote, as the government was locked in crisis.

Dutton told reporters: “I called the prime minister to advise him that it was my judgement that the majority of the party room no longer supported his leadership.

"As such, I asked him to convene a meeting of the Liberal party at which I would challenge for the leadership of the parliamentary Liberal party.”

He said he would not have contacted Turnbull if he did not have majority support.

But Turnbull at that point was holding out, his camp arguing that Dutton supporters had not shown they had majority support – 43 MPs.

The Dutton camp circulated a petition on Wednesday night for a meeting. The canvassing has been accompanied by inducements and arm twisting by the Dutton campaign. The number who have signed the petition is unknown.

Victorian MP Sarah Henderson said she had been offered a frontbench position if she supported Dutton. “Just imagine if that was accepted and there was a change of leadership — to be rewarded for an act of treachery, I think is a terrible thing.”

Senior ministers were bunkered down in Turnbull’s office before the press conference by the three ministers.

Two more frontbenchers resigned earlier Thursday – Zed Seselja assistant minister for science, jobs and innovation and Michael Sukkar, minister assisting the Treasurer. They were among the multiple ministers who offered to resign earlier this week but did not have their resignations accepted.

With serious doubt over his constitutional eligibility to sit in parliament, Dutton released legal advice that he had sought last year. This relates to whether his interest in childcare centres through a trust breaches section’s 44 provision on conflict of pecuniary interest.

The advice argues that Dutton has no conflict. Releasing it on Thursday morning, Dutton said “there has never been any doubt about my eligibility”. He said a “spurious and baseless campaign” had been waged against him on the matter.

Dutton supporter Craig Kelly said if there was any doubt about the matter it could be settled by selling the childcare centres.

Manager of opposition business Tony Burke said: “There are really serious question marks over whether or not the man who wants to be prime minister of Australia later on today is even eligible to be a member of parliament.”