As a result, he failed in the mission and emerged from Wednesday's all-night sitting with his authority diminished. With time almost out before the election, this legislation, which he claimed was "very important", has reached a dead end.

First, Morrison thought he could tactically outplay Anthony Albanese, wedging Labor on an electorally sensitive issue. This smacked of hubris - it is safer to think your opponent just might be smarter than you are.

Second, he underestimated the spine of the moderates in his own party. He was not properly tapped into his backbench, especially those in the leafy suburbs who are under pressure from independent candidates.

Third, Morrison believed he could rush a complex issue - which he's had years to deal with - in the high-pressured dying days of the electoral term. The "I am PM - therefore I can" principle doesn't always work in a close Parliament.

This has been another political shambles for Morrison, who is already beset by bad polling, a crisis in aged care, and leaked texts.

NSW Premier Dominic Perrottet - incidentally, a dedicated Catholic - had some prescient words on Wednesday as the federal government prepared for votes on the religious discrimination bill and associated legislation.

"I've made it very clear that I don't believe legislation in this space is necessary and I think it can end up creating more problems than it solves," Perrottet said.

As well as arguing it is needed, Morrison said he was committed to the legislation because he promised it before the last election.

In reality, he has been substantially driven by a quest to keep or win faith-based conservative voters, particularly in ethnic areas in western Sydney. Some Coalition sources believe these votes were an essential component in his 2019 victory.

Albanese desperately requires these votes too - Labor identified after the 2019 election that it had a problem with them - and he certainly can't afford to lose those already in the ALP's camp.

So although many in Labor and its base didn't want a bar of the religious discrimination legislation, the Opposition Leader wrangled a divided frontbench and caucus into supporting it, while pressing amendments.

The government's package included an amendment to the Sex Discrimination Act to prevent gay students being expelled from religious schools.

But that was narrower than an earlier undertaking Morrison gave, and it didn't cover transgender students. The government said it wanted a report from the Law Reform Commission before acting on them, because of what it insisted were the complexities of religious schools dealing with trans students.

The exclusion of transgender children turned out to be a serious flaw in the eyes of some in Liberal ranks.

The moderates asserted themselves, in negotiations on the package before the parliamentary debate, and in the chamber. They were driven by principle, but also by their own political imperatives.

Some moderate critics of the bill share Perrottet's view about the unwisdom of stirring up the religious discrimination issue. They were even more exercised about transgender students being left in limbo.

Morrison twisted arms and gave some sops to try to corral his followers. Perhaps he thought when push came to shove, his authority would get him through.

It didn't. Two Liberal defectors, Bridget Archer and Trent Zimmerman, raised their heads in votes on the main bill, although it eventually passed the House of Representatives unamended.

It was a much worse story for the government on the bill to amend the Sex Discrimination Act. Three more Liberal rebels - Katie Allen, Fiona Martin and Dave Sharma - joined Archer and Zimmerman. The five supported a successful amendment for all students - including transgender students - to be protected.

Morrison was left flummoxed and furious. The government was uncertain how votes would go if the legislation went to the Senate, with Liberal senator Andrew Bragg set to cross the floor.

Meanwhile the Australian Christian Lobby declared the government should withdraw the package.

After a few hours of Thursday morning mulling, the government shelved the package, and lashed out. Attorney-General Michaelia Cash argued in a letter to her Labor counterpart, Mark Dreyfus, and crossbencher Rebekha Sharkie, who moved the successful amendment, that the change could in fact allow - rather than prohibit - discrimination in religious schools.

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The government said this was based on advice from the government solicitor, although the letter did not reference the advice. Sharkie was unimpressed, describing Cash's letter as a "ruse". She challenged Cash to table the legal advice.

The humiliating loss of the parliamentary vote has bitten deeply with Morrison and senior ministers. The government doesn't bring things to a vote without being confident of its numbers.

Defence Minister Peter Dutton on Friday put the boot into the defectors, saying people had broken their word. Morrison was "misled", Dutton told the ABC. Undertakings had been given and not honoured.

The religious discrimination package won't get through this term. There are only a couple of Senate sitting days left (in budget week), the government doesn't have the numbers, and the political caravan will have moved on.

As for now, Morrison might argue he tried but was thwarted by Labor. But that can be countered with a question and a proposition.

The question is: "Why did you leave it so late?"

The proposition is that, regardless of the legal argy-bargy, when you are promoting anti-discrimination it is difficult to complain you have been stymied by the House of Representatives insisting on removing discrimination against trans kids.

This botched bid to legislate against religious discrimination has been a textbook example of poor policymaking. And that's leaving aside the problematic nature of the case for the policy in the first place.