Attorney-General Christian Porter continues out of sight on stress leave as he contemplates his future with his greatest ambition shattered.

There can be little doubt that his tears of anger and frustration at what he considers the unfairness of it all are as much prompted by the ending of his dream to become prime minister, as everything else.

Malcolm Turnbull, in the autobiographical account of his prime ministership A Bigger Picture, recounts a confrontation with Mr Porter in the days before the Peter Dutton coup that saw Scott Morrison come through the middle and snatch the leadership crown.

“The only emotional part of our discussion,” Mr Turnbull writes, “was when, utterly unprompted, Porter started to tear up at the other side of my desk as he bemoaned the narrow 2 per cent margin by which he held his seat and how he was now inevitably going to lose it.

Christian Porter outed himself as the accused rapist, but denies all the allegations.

‘‘‘I didn’t come here to do this. I came here to sit in your chair, and now I’m going to lose it all’, he moaned.”

Mr Porter on several accounts grew up with the conviction his destiny was to be prime minister of Australia.

He left a senior ministerial position in Western Australia at a time when he was heir apparent to then premier Colin Barnett to progress his Canberra ambition.

Though he said last week he has no intention of standing down as Attorney-General or quitting politics, he must realise that seeking to lead the Liberal Party and the nation with an unresolved doubt he is an alleged rapist hanging over him is a bridge too far.

Indeed Mr Turnbull, a bevy of senior lawyers, Labor, the Greens and most of the crossbench are calling for an independent inquiry to address that doubt.

Labor’s shadow attorney-general Mark Dreyfus says an inquiry could clear Mr Porter’s name because at the moment a preliminary police investigation has had to be ended “because of course the complainant is no longer with us”.

Mr Porter, however, is probably correct when he says such an inquiry couldn’t achieve an outcome to definitively clear him, and there is some precedent for this view.

In 2002, George Pell when Archbishop of Sydney, stood aside while a retired Victorian Supreme Court judge Alec Southwell inquired into claims by a Melbourne man Cardinal Pell had sexually assaulted him 41 years earlier.

Mr Southwell was not satisfied the “complaint had been established”, though he found the accuser had “spoken honestly from actual recollection”.

Cardinal Pell claimed exoneration and returned to his role while the complainant’s solicitor said his client had been vindicated.

Such an outcome would still leave Mr Porter, the first law officer of the land in an untenable position, for unlike Pell, the attorney’s political opponents would be sure to keep reminding voters about the cloud over his reputation.

Scott Morrison says there is “not another process” to investigate allegations of rape against Christian Porter.

Just as the Liberals were quick to draw comparisons between Labor’s Bill Shorten and Mr Porter’s predicament as soon as the allegations against the Liberal minister emerged – never mind that the Labor politician had faced an extensive police investigation of the rape claims against him.

In the end the calculus will be a political one – not what is fair to Mr Porter, but what is best for the government.

The Four Corners program on Monday night would have given many, more reason to doubt Mr Porter’s denials.

Mr Morrison’s tactic of having Mr Porter and his other embattled minister Linda Reynolds out of view and away from the probing questions of Parliament is at best a time-buying exercise, at worst even more damaging of the government’s credibility.

The political calculus will be how long the Prime Minister judges his government can take water while Mr Porter remains on board – and how big a risk it would be to sack him.

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Mr Porter’s fate is much more problematic than Senator Reynolds.

If he quits Parliament there would be a loss of absolute majority and a by-election in a marginal seat.

If Senator Reynolds quits the Senate she can be replaced with another Liberal appointed by the Western Australian Parliament – there are sure to be quite a few putting up their hands after next weekend’s state election.

In the meantime, the Prime Minister will be sweating on just exactly what the Attorney-General with his shattered dreams meant when Mr Porter said he was seeking support and assistance for something that he didn’t expect to happen to him in a million years and that “I’m sure it will change my views on a whole range of things”.

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