The last few weeks have been a litany of horrors for the Abbott government. First there was the Bishop affair, with Abbott and Bishop digging in their heels until the PM’s personal choice of Speaker – openly partisan, according to many – was finally forced to go.

Then followed the stories from Nauru: allegations of waterboarding; the rape of a detainee; statements by senior pediatric staff at Nauru that the new regulations allow the cover-up of child abuse. Allegations that Australian Greens Senator Sarah Hanson-Young was followed and spied on by security staff during her entire visit to the island nation, and records of it shredded when this was exposed.

In July, Four Corners reported that in 2005, a Mafia figure from Italy, who had initially been refused residency in Australia on the grounds of his activity with and connections to organized crime, had his residency approved by then Immigration Minister Amanda Vanstone after paying thousands of dollars in donations to the Liberal Party. It raised awkward questions.

Last week, a five-hour debate on same sex marriage ended with Abbott directing that MPs vote along party lines on the issue, but the cost was high. Open divisions appeared, with Turnbull even more energetic and Pyne now also highly critical.

The following day, a decision by the Supreme Court in an internet piracy case undermined the government’s entire anti-piracy program and its relationship with powerful international media giants. A previous decision by the court created the expectation (and fear) that abusive pursuit of downloading damages by ‘piracy trolling’ firms would be extended to Australia. The new decision by Justice Perram of the Supreme Court of New South Wales basically destroyed all possibility of such activities ever being allowed in Australia, and set a strong and rational international precedent.

Finally, on Thursday came the news that Dyson Heydon, the commissioner of the Royal Commission into Trade Union Governance and Corruption, had agreed to speak at a Liberal Party fundraiser. The facts are this. At some time in the past, Commissioner Heydon was asked to give the memorial Sir Garfield Barwick address, which is hosted by a lawyer’s branch of the NSW Liberal Party. The present Attorney-General, George Brandis created the event and gave the first speech in 2010. An email inviting the Commissioner to speak dated March 2014 clearly stated it was a Liberal Party fundraiser. On 4 April, a letter was sent to Heydon which had a Liberal Party header and stated on the back that any profits would go to Liberal Party state campaigning. To describe the dinner as a ‘fundraiser’, though, is rather incorrect. The $80 a head ticket price would not make a great deal of profit; fundraising events charge more like $2,000/head. However the ticket fee can be claimed against tax as a political donation; technically it is a fundraiser and was described as such. On 13 August, only a few hours before the story broke, the Commissioner’s office sent an email which the Commissioner subsequently claimed said that he withdrew from the speech. From what we know, however, the email merely said that Heydon would be unaccompanied, that he would not answer questions, and that he would not be able to speak ‘while he was Royal Commissioner’ if it was described as a Liberal Party fundraiser. Ironically, union fundraisers have been one subject of enquiries by the Commission.

Tony Abbott has in the past used legal means to attack opponents and has appointed Royal Commissions that were heavily criticised. Legal means were used to attack Pauline Hanson and Julia Gillard. The Commission Of Audit, which he appointed at the beginning of his reign, was dominated by the abovementioned Amanda Vanstone and conservative public servants, and was widely regarded as a mere rubber stamp to for the government to proceed with a razor gang program. The appointment of the deeply conservative Heydon was also regarded as politically biased by some. Heydon is an outstanding and respected member of the legal profession whose integrity is not questioned, but his conservative views are well known. Nevertheless, the Labor Party played along.

The Commissioner is now, in effect, under investigation himself, and the Commission is hamstrung. A survey of media shows near unanimous agreement that the Commissioner’s position is completely untenable and he must step down; an internet poll in the Sydney Morning Herald shows that almost 90 per cent of respondents say that he should step down. If he does, the Commission itself must be wound up, as the letters patent that created it are personally addressed to Heydon. As Heydon himself said in a previous case, the question is not whether a judge is biased but whether he is seen to be biased. Whether or not the affair was a Liberal Party ‘fundraiser’ as such, any profits were clearly stated to go to the Liberal Party, and the semi-withdrawal mere hours before the story broke is not very convincing.

Abbott’s instinct will be to support the Commissioner, and Heydon’s instinct will be to hang on. This is a mistake: it seems unlikely that he will survive past the end of this week, and he should resign as quickly as possible. His career is also unlikely to survive, whether he answers the questions raised about this issue or not.

For Cabinet, this is yet another crisis following weeks in which they have been in continuous damage control mode. Their performance in a recent Question Time is suggestive. Abbott seems haggard and exhausted; Hockey looks surly; Julie Bishop and Pyne look like they would rather be anywhere else. That is understandable. Day after day they have been waking to hope for a clear day working on politics. Day after day, they have been forced to cover for Abbott’s mistakes. The situation is now unsalvageable.

The legal campaign against Shorten and Labor is smashed and will not be able to be revived for at least two years. The PM’s plan to call an early election while Shorten’s name was blackened is in tatters, with Shorten now looking like a victim of a smear campaign. Moreover, as the entire Cabinet backed the appointment of Heydon, they will be looking for someone to blame. Turnbull is in almost open revolt. Bishop has said nothing against Abbott but has subtly positioned herself as a contender. Pyne, always supportive in the past, has been increasingly critical. Scott Morrison is also emerging as a possible contender. The situation is assuming the proportions of a Greek tragedy, with Abbott’s own hubris making him an isolated figure with little support anywhere. And this is also why Heydon and Abbott are forced to try to tough it out. If the Commission falls, it seems almost certain that it will take Abbott along with it.

If a spill motion arises, it is likely to do so after the forthcoming WA Canning by-election on 19 September. Though the Liberals are likely to retain the blue ribbon seat, the death of the longstanding and popular MP Don Randall and other factors mean that the majority is likely to be much reduced. A bad result would make a plausible trigger for a leadership challenge to Abbott.

Who would win such a challenge? Although the public would support Turnbull, he is considered too moderate: furthermore, he has already had a chance as leader. Morrison is too right-wing; the party will want to move to the centre to try to create a new inclusive, consultative party room. That would mean Bishop or Pyne. Bishop would ring the right bells with the electorate, but she lacks some things a lot of Libs consider vital – specifically, a thing between her legs. Nevertheless she seems the most likely winner at present, which would be bad news for Labor.

It seems to me a clear possibility that we could see a new leader in parliament by October.