WE'LL not see the parties' election manifestos for a couple of weeks. When we do, one will command a lot more interest than the others.

The SNP is so far ahead in the polls, it will take an extraordinary, unforeseeable turn of events to deny it a comprehensive victory on May 5. So the SNP's manifesto will be viewed more as a programme for government than a vote-winning wish list.

That might lend it a cautious flavour. And no bad thing, you might think, if you cast your mind back to 2007 when the party came to power on the back of some fanciful pledges it expected to be bargained away in the course of coalition talks.

We should not be surprised if Nicola Sturgeon is most cautious about her party's core policy: independence.

For years the SNP has avoided making a song and dance about independence during elections in order to broaden its appeal. This time there is even more reason to be circumspect.

The party is wrestling with how to "refurbish " - as Alex Salmond put it - the economic case for Scotland leaving the UK.

Mr Salmond's imagined address to the nation on what, in the event of a Yes vote 18 months ago, would have been independence day was telling.

He envisaged the birth of an independent Scotland that had been denied a currency union with the rest of the UK.

Mr Salmond spent the referendum campaign accusing George Osborne of "bluff, bluster and bullying," after the Chancellor ruled out his plan to share sterling in a formal currency union. It seems now it wasn't Mr Osborne who was bluffing.

Mr Salmond's comments will make it very hard for the Nationalists to resurrect the idea of a currency union in a future referendum campaign. But judging by an interview Mr Salmond gave to the BBC, that's no longer part of his thinking anyway.

He spoke of reaching a position that could not be "gazumped" by his opponents: in other words, a policy that could withstand whatever the UK government threw at it.

In his 'independence day' speech, Mr Salmond imagined Scotland using the pound on an ad hoc basis, known as 'sterlingisation,' with a view to creating a separate currency at some point in the future.

Whether this is where the SNP ends up on the currency remains to be seen. Other questions, particularly about the state of the public finances, will also have to be addressed, as several pro-independence commentators have recognised.

But now is not the time to for the party to expose weaknesses in the economic case for independence to public debate and scrutiny.

Nicola Sturgeon took care to punt the issue into the long-ish grass during the party's pre-election conference in Glasgow, promising activists an independence initiative in the summer.

They cheered as if 'indyref2' had been announced but, reading between the lines, what Ms Sturgeon seemed to be proposing was part of a wider exercise to reframe the argument for leaving the UK.

Will the lack of focus on independence demotivate the SNP's battalions of footsoldiers? Not a chance with an election to win. But, after that, they will expect progress towards a second referendum.