Make no mistake about it, the stakes could not be higher for Scott Morrison and the government at Saturday’s Wentworth by-election.

A loss would be devastating, stalling any momentum some glean from the published opinion polls.

A nail-biting win with a huge swing close to the 17 per cent margin would be a huge relief, except it would spook Liberal and National MPs on much smaller margins. The sort of scare that induces panic and can destabilise the show.

The absolute best result for the PM would be a Liberal win with the swing contained to single digits.

Independent candidate Dr Kerryn Phelps is proving popular. Photo: AAP

One thing a loss will not do is end Mr Morrison’s reign as prime minister.

He will lose his one-seat majority but not government.

Two crossbenchers have said they will support confidence and supply. So too has the independent candidate Dr Kerryn Phelps.

Indeed, Dr Phelps is the target of much of the Liberals’ negative campaign. She is a threat, showing up strongly in seat polls and in the Liberals’ own research.

Mr Morrison is warning “with independents, you certainly don’t know what you’re ever going to get. It’s like the good old box of chocolates, you never know what you’re going to get, when it comes to voting independent”.

The third Liberal prime minister in five years says with his party “you know what you’re going to get”.

And that’s his problem: Five years of debilitating internecine warfare.

Bill Shorten homed in on this vulnerability in Parliament.

Labor leader Bill Shorten will be watching the by-election results with great interest. Photo: AAP

The Labor leader noted that the PM was warning a vote for anyone other than the Liberal would “destabilise the government”. But he asked “didn’t the Prime Minister destabilise the government in the first place when he and his colleagues deposed Mr Turnbull? Isn’t government instability the only reason we are having a by-election in Wentworth?”

Mr Morrison, taking comfort from his greater personal popularity than Mr Shorten in the latest Ipsos Fairfax and Newspoll said “The one thing Australians don’t want” is the Labor leader.

But by any polling analysis Australians don’t want the Liberals and Nationals. A measure of the folly of knifing Mr Turnbull is Mr Morrison’s unique failure to dramatically lift his party’s support.

There was no repetition of the sort of lift the Liberals got when they ditched Tony Abbott.

Six weeks after the demise of Mr Abbott, the Liberals’ primary vote had shot to an astonishing 45 per cent.

Seven weeks after this latest change, their primary vote is 37 per cent, it trails Labor and is lower than at the election.

The handling of sexual discrimination against gay school kids is a debacle that will hardly convince voters that Mr Morrison’s instincts are immediately in tune with community sentiment, especially in socially progressive Wentworth.

The Prime Minister took 48 hours to completely reverse his original stance of supporting the leaked recommendations of the Ruddock expert panel. So religious schools will not be able to discriminate against students on the basis of their sexuality, but what about teachers?

There is no doubt the conservatives’ demands about freedom of religion after the overwhelming success of the marriage equality phone plebiscite have backfired spectacularly. That survey showed most Australians no longer tolerate prejudice against same-sex-attracted people.

The Ipsos poll found 74 per cent of Australians oppose laws allowing this discrimination in faith-based schools. Mr Shorten moved quickly on Sunday night with his leadership group to include teachers.

This appears a bridge too far for Scott Morrison. He will not be quickly matching Labor “to ensure teachers can’t be sacked because of who they are or who they love”.

Mr Morrison told Parliament “there would be a time and place to address those issues.” That will be after the by-election and he won’t be releasing the Ruddock report before then either.

His candidate, Dave Sharma, not so reticent, says he’s “fundamentally opposed to discrimination in schools for teachers and pupils”.

Whether that helps save the day for his prime minister is the big question.

Paul Bongiorno AM is a veteran of the Canberra Press Gallery, with 40 years’ experience covering Australian politics.