Nicola Sturgeon warned this week she could turn the next general election into a "de facto" referendum on independence.
But already that strategy is running into trouble.
It's not up to the SNP to decide what a general election should be used for.
Voters can cast their ballot in any way they want.
On a basic level, an election is about choosing a party to form the next UK Government.
Or as Professor James Mitchell put it yesterday: "There are elections and there are referendums and they are quite distinct.
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"In an election, the voter is allowed to choose what she or he wishes to choose to determine their vote.
"It doesn't have to be about one issue - and it rarely is about one issue. It's not for a political party to dictate the terms of an election.
"In a referendum, the question is very clear and that is the whole point."
Professor Mitchell is no hardline Unionist. He literally wrote the book on the SNP's extraordinary rise to power.
He correctly points out that people are motivated by a whole range of different things when they decide who to back at an election.
Whenever the next general election happens - it could be next year, it could be 2024 - many voters will be looking to kick-out Boris Johnson and his Tory party given their dismal record.
Labour is in the strongest position to offer a genuine alternative in Downing Street.
At the time of a cost of living crisis, the First Minister could ask Scots to ignore all that and focus their minds on independence instead.
The SNP leader has explained she doesn't want to go down that path unless absolutely necessary.
Her preference is to hold an IndyRef2 on October 19 next year.
She has asked the UK Supreme Court to rule on whether her government has the powers to hold such a vote.
There is a very real chance that judges will decide it does not.
That's when the SNP's Plan B would then kick-in.
It would campaign at the next general election on a single issue - vote for us if you want to end the Union.
But awkward questions remain.
What happens if the SNP's vote share drops compared to its result in 2019?
Does the party still have a mandate to negotiate independence if it elects fewer MPs?
Imagine a scenario where the SNP emerges, for the third general election running, as the largest party in Scotland in terms of votes and seats.
Nicola Sturgeon duly declares this is a mandate to start talks with the newly formed UK Government.
The SNP travels to 10 Downing Street and knocks on the door - but no one answers.
There is no legal basis to declare independence on the back of a general election result.
Whoever is in power in London could simply ignore SNP calls for negotiations.
The party would be no further forward on the path to independence than it is today.
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