MALCOLM Turnbull’s leadership is looking increasingly shaky as Cabinet leaks threaten to derail the Prime Minister’s authority.

Details of Tuesday’s Cabinet meeting were revealed in the Daily Telegraph, which reported that ministers were backing a banking royal commission despite opposition from Mr Turnbull and Treasurer Scott Morrison.

It follows a report in The Courier-Mailthat the government would reject the Uluru statement on indigenous representation.

In an interview this morning, Today host Karl Stefanovic pointed out Cabinet was “leaking like a sieve” and asked frontbencher Christopher Pyne whether he was the source.

Mr Pyne denied being involved and said the Turnbull Government had been a “good, solid methodical government” and Cabinet needed to be “tight and united, which it has been”.

But Stefanovic was not convinced, pointing out: “As soon as Cabinet starts leaking it’s the end.”

In a column in The Conversation, political journalist Michelle Grattan noted that Cabinet leaks during the Abbott Government’s reign in 2015 were mostly inspired by those wanting a coup.

But she noted: “This time, the ‘who’ and the ‘why’ aren’t clear. There is no evidence of any organised push against Turnbull, like there was against Abbott, although leadership speculation has become media grist”.

She said the leaks could be driven by general angst around or reflect jostling by various players in uncertain times.

But Grattan wondered why Foreign Minister Julie Bishop would support a formal investigation into the leaks, which just highlighted the breakdown in government discipline.

Ms Bishop was another minister grilled on the leaks and she has denied having anything to do with them.

“Let me ask bluntly, were you the leaker?” 7.30 host Leigh Sales asked her on Thursday.

Ms Bishop replied: “No, I was not. Absolutely not.”

Earlier this week there was speculation that Ms Bishop was plotting a leadership challenge against Mr Turnbull with Scott Morrison as her preferred deputy.

But Ms Bishop backed Mr Turnbull and rejected the idea that his time would be up if the government lost 30 Newspolls in a row. Mr Turnbull famously used Mr Abbott’s loss of 30 Newspolls in a row to justify his own leadership challenge.

“The only poll that counts is the one on election day and we’ve got 18 months until the next election,” Mr Bishop said.

Pressure is mounting on the Prime Minister as the dual citizenship saga continues to force the resignation of members of Parliament, leaving control of the House of Representatives on a knife-edge.

National political editor of The Australian, Simon Benson believes Mr Turnbull has entered the “danger zone, with every utterance from cabinet colleagues being viewed through a prism of leadership and positioning”.

He reports that there is now a “more serious tone to the chatter that began two weeks ago”.

“The view among the senior ranks of government is that the Bennelong by-election could become the catalyst,” Benson writes.

“In the unlikely, but possible, event that the seat is lost, Turnbull’s survival becomes deeply questionable.”

Liberal MP John Alexander is fighting to retain his seat in Bennelong after he was found to be a dual citizen. His re-election has become more challenging after Labor decided to field the formidable former NSW premier Kristina Keneally as a candidate.

Adding to the sense of crisis is a report this week from NewsCorp columnist Andrew Bolt, who reported that an unnamed Coalition MP intends to step down from the government and sit as an independent when parliament returns unless Mr Turnbull is replaced as prime minister by someone who appeals to conservative voters — and not Ms Bishop.

Mr Turnbull is remaining stoic and has declined to comment on “gossip” about cabinet leaks.

“But I can assure you that I take the security of cabinet discussions very, very seriously indeed,” he told reporters.

But Labor is seizing on the controversy with leader Bill Shorten saying Ms Bishop’s comments were “astonishing”.

“First of all she has confirmed that the cabinet is leaking on itself. But what is more astonishing that Julie Bishop has chosen to call for an investigation into her colleagues,” Mr Shorten said.

“The Turnbull cabinet is eating itself and Julie Bishop has said she doesn’t have confidence in her cabinet colleagues. Why should Australians have confidence in the Turnbull cabinet?” Treasurer Scott Morrison said it was important “these issues are resolved”.

“That’s a matter I’m sure the prime minister has well in hand,” he said.

Immigration Minister Peter Dutton said he had a “gut feeling” who was leaking, but did not name the colleague.

“If people believe that somehow their careers are furthered by leaking or by trying to put out something that’s going to damage the government or damage me or damage Malcolm, it says more about them than it does about us,” Mr Dutton told 2GB radio.

— with AAP