THE SNP's ruling body last weekend put forward a course of action they don't do very often: an alternative to a strategy set out by party leader Nicola Sturgeon.

The new option proposes that instead of fighting the next Westminster election as a de facto referendum it should head into the poll seeking a new mandate for an agreed referendum (as the party has previously done). And should an agreement on Indyref2 not be reached following the SNP winning a majority of Scottish seats, then the party would fight the next Holyrood election in 2026 as a de facto referendum.

It marked quite a shift in thinking since Ms Sturgeon set out her strategy in June last year and it will be a major crossroads for the SNP when the party meets in March for its special conference to decide which option - indeed if either - to back.

The First Minister unveiled her route map just before Holyrood went into its summer recess in a bid to block what she saw as an impasse due to the UK Government's refusal to agree a new independence vote.

READ MORE: Expert warns SNP of consequence over a de facto vote climbdown on FM

In the absence of willingness by successive Prime Ministers since David Cameron to grant a Section 30 order, she had committed ahead of the 2021 Holyrood election to a bid to use devolved powers to stage Indyref2 in the next parliamentary term.

But in the months which passed the SNP's election victory, there was no sign of the required bill.

On June 28 it became why: the Lord Advocate was uncertain whether Holyrood actually had the powers to hold the promised referendum with the matter to be referred to the Supreme Court for legal clarity.

So, having made an election pledge to voters, the Scottish Government had then to come up with a second fall back plan should the judgement not go in its favour. Hence the birth of the "de facto referendum".

"If it transpires that there is no lawful way for this Parliament to give the people of Scotland the choice of independence in a referendum, and if the UK Government continues to deny a section 30 order, my party will fight the UK general election on this single question: should Scotland be an independent country?" the First Minister told MSPs. 

READ MORE: Sillars calls for Sturgeon to ditch SNP's de facto referendum plan

"The path that I have laid out today is about bringing clarity and certainty to this debate. Above all, it is about ensuring that Scotland will have its say on independence. I want the process that has been set in train today to lead to a lawful constitutional referendum, and for that to take place on 19 October 2023. That is what we are preparing for. However, if the law says that that is not possible, the general election will be a de facto referendum. Either way, the people of Scotland will have their say."

Some commentators and experts, including the Edinburgh University academic Professor James Mitchell raised their eyebrows pretty quickly. Professor Mitchell made clear that in his view there was “no such thing as a de facto referendum” and that elections and referendums “are quite distinct” within hours of the FM's statement. 

The SNP though appeared to embrace the strategy with Jim Sillars, often one of the most high profile critics of Ms Sturgeon, sympathetic to the plan (though he has now changed his mind). Dennis Canavan, who chaired the Yes campaign in 2014, also backed Ms Sturgeon's route map though noting there was "an element risk".

However, attitudes began to shift during the summer and autumn as the UK political landscape changed in ways most wouldn't have predicted.

On June 28 when the de facto plan was unveiled by Ms Sturgeon, Boris Johnson was still Prime Minister.

READ MORE: SNP MP says 'world watching' debate on de facto independence vote

Despite the partygate scandal it seemed at the time that he would hold on to his job and take the Tories into the next election possibly even winning a new term.

Against such a backdrop the SNP considered winning more than 50 per cent of votes while standing on the single question of independence an ambitious but realistic goal.

After all the party had managed it before. In 2015 when the SNP won a record 56 out of 59 seats at the general election it took 50 per cent of votes. With the Greens the total votes for the two independence supporting parties came to 51.3 per cent.

But within months Mr Johnson had resigned to be replaced for a brief stint in Downing Street by Liz Truss whose disastrous mini Budget caused a major economic crisis and sent interest rates soaring.

By the time Rishi Sunak replaced Ms Truss in Number Ten in October, polls had predicted a Labour landslide at the next general election and also suggested the SNP would fall short of winning a majority of votes in Scotland needed to declare a de facto referendum win.

It was also becoming clear to some in the SNP that a proportion of their supporters may be minded to switch to Labour with the party stressing in their view the general election was not about the constitution but removing the Tories from power.

Nevertheless, following the Supreme Court's ruling in November that Holyrood did not have the powers to hold Indyref2 without Westminster's agreement, the FM stuck to her plan insisting the next general election would be a de facto referendum.

By then, many figures in the party, particularly its MPs, were having severe reservations. In a sign of the malaise Ian Blackford, a close ally of the First Minister, saw himself replaced as SNP leader in Westminster by Stephen Flynn.

The MPs have not been shy in expressing their fears. SNP MP Pete Wishart warned last week using the GE as a de facto referendum was a "massive gamble" which risked which risked killing off independence. Though he still backed the plan.

Activists too have been spelling out the dangers for the SNP and wider independence movement; that there is no guarantee that even if the party (along with the Greens and possibly Alba) won more than 50 per cent of the vote, the new UK Government, whether Tory or Labour, would recognise the result as they dispute the SNP's premise that the election is a referendum.

However, some fear in the world of politics it is likely that should the SNP (and other Yes parties) not get the required result, the UK parties would well celebrate a SNP loss. And with two defeats in two decades, UK ministers are unlikely to grant the "gold standard" agreed vote, which is after all the SNP's first preference.

Alternatively, if SNP delegates decide to park the plan when they meet in March, they would be rebelling against the leader's own strategy.

Could Ms Sturgeon survive the loss of authority such a vote against her proposal would mean? She probably would, though the suggestions in party circles are that there would have to be a change of leader if she lost the general election if it was used as a de facto referendum.

But perhaps the biggest risks SNP delegates will be weighing up is whether the independence campaign could outlive two referendum "losses" in a decade and what would happen to the ambition for holding the gold standard vote if the fall back plan to the fall back plan turned out to be a dud?