Malcolm Turnbull's 11-week-old prime ministership is facing a serious character test heading into the final day of Parliament for the year, with one of his hand-picked ministers hanging by a thread after offering contradictory explanations for his role in the Ashby/Slipper affair.

Labor stepped up its attack on the Special Minister of State Mal Brough on Wednesday, launching two unsuccessful censure attempts and directing repeated questions at the embattled minister who stands accused of having actively sought copies of the private diary of then speaker Peter Slipper in 2012, and of subsequently misleading the Parliament this week when questioned on it.

Prime Minister Malcolm Turnbull and Mal Brough during question time on Wednesday. Photo: Alex Ellinghausen

Procuring the private documents of a Commonwealth officer is a criminal offence.

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Mr Turnbull was standing by his minister, and key backer, on Wednesday, arguing that merely claiming a minister had misled the Parliament "did not make it so".

But even within the government, Mr Brough is increasingly isolated with fellow cabinet ministers conceding privately that his position is an embarrassment.

Illustration Matt Golding

Some go further, noting with derision that Mr Turnbull had appointed Mr Brough to a portfolio charged with the maintenance of MPs' standards while still under a cloud.

With an ongoing Australian Federal Police investigation over whether Mr Brough had asked Mr Slipper's then aide James Ashby to supply copies of the Speaker's diaries, Labor called on Mr Turnbull to sack the minister, accusing him of deliberately misleading the Parliament.

Mr Brough had told the Nine Network's 60 Minutes program last year that he had asked Mr Ashby to obtain copies of relevant diary pages because he believed the then Speaker had committed a criminal offence.

Asked by the program's Liz Hayes if he had asked Mr Ashby to procure the diary pages, he answered, "Yes, I did".

But he has since told Parliament that not only did he never seek the diary pages, but that his answer to 60 Minutes had been selectively edited.

That was shown to be false when the raw transcript of the interview was furnished by the network and showed there had been no material element edited out.

Smelling blood, Labor probed the contradiction, eventually resorting to asking the exact same question that had been asked by Ms Hayes, to which Mr Brough then answered "no".

Opposition Leader Bill Shorten, who was travelling back to Australia on Wednesday evening, said the affair revealed the government's true nature.

"Malcolm Turnbull must be the only person in Australia who believes a word of what Mal Brough says," he said.

"It's about his judgment in appointing Mal Brough as Special Minister for State in the first place, making him responsible for government integrity of all things.

"It's time for Malcolm Turnbull to show some leadership, admit he got this wrong and sack Mal Brough."

Earlier in the day and under mounting pressure, Mr Brough had offered a highly qualified explanation to Parliament on Wednesday. "In relation to the 60 Minutes interview, what was put to air was not the full question," he began.

"Mr Speaker, my recollection of the interview was that the question was put to me in a somewhat disjointed manner, and I answered the question without clarifying precisely what part of the question I was responding to. This is confirmed by the tape provided by 60 Minutes and that was the reason for my answer yesterday.

"Mr Speaker, I have taken the opportunity to review the tape and transcript, and apologise to the House if my statement yesterday unwittingly added to the confusion rather than clarifying the matter."

But if the statement was meant to calm the storm, it backfired with Labor ratcheting up its calls for Mr Turnbull, just back from the Paris climate talks, to cut his minister loose.

The scandal threatens to widen and could yet embroil other Coalition figures including the manager of government business and Minister for Innovation Christopher Pyne and Assistant Minister for Innovation Wyatt Roy.

Government sources concede Mr Turnbull is weighing the pros and cons of trying to ride out the final day of Parliament and hope the furore dies down once the theatre of Parliament is no longer available to the opposition, or, on the other hand, nipping the controversy in the bud by simply giving the opposition a cabinet scalp.

But a midway option is also under consideration, that of standing Mr Brough aside pending the outcome of the police investigation.

In a sign of the danger to Mr Turnbull's nascent leadership, which has otherwise gotten off to a strong start with voters, Mr Turnbull told the Coalition party room on Wednesday that the government did best when it was not speaking about itself but about middle Australian voters.

But critics remain, including many loyal to the former prime minister Tony Abbott.

Conservative strongman Cory Bernardi became the first MP to put his name to the Brough controversy by suggesting Mr Turnbull should take "all events into consideration" as he considers the future of his "captain's call" in promoting Mr Brough.

Senator Bernardi said that "in the end of the appointment of ministers is always a captain's call".

"I'm sure the current captain will take all events into consideration in determining Mr Brough's future," he said.

With James Massola

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