Making the case for independence: it's the economy, stupid

It's the economy, stupid.

A slogan, first pinned on a wall by the Clinton campaign team, has passed into political history.

And it's currently being deployed by the Scottish National Party at their conference in Aberdeen. They may not use the phrase, but it's what they are pinning their hopes on.

Why? Because the latest survey by the authoritative National Centre for Social Research (NatCen) suggests Scots are rethinking their reservations over independence.

A majority now believe that leaving the UK would make Scotland's economy better, a turn around from opinion at the time of the independence referendum.

For Nationalists aware that the economic case for leaving the UK was a weakness in 2014 this latest poll information is therefore good news.

Nicola Sturgeon is refusing to say when she will call a second independence vote despite my pressing her to do so in my recent interview with her for Representing Border.

But she has said she wants to kickstart the debate on the benefits, as she and her party see them, of Scotland leaving the Union.

It's a message that a procession of senior nationalists have been hammering home in Aberdeen. It's been said so often, so repetitively, that it's clearly the party line.

But while this is good news for the party SNP there are a number of problems for it in formulating a new independence offer for Scots.

The first that there is a debate going on over what kind of economic policy the party will pursue.

A Growth Commission under former MSP Andrew Wilson proposed a program of debt and deficit reduction for an independent Scotland, which has been attacked by some in the party as a recipe for 'neo-liberalism'.

The First Minister maintains that it is nothing of the sort, that you can reduce your deficit and end austerity at the same time by growing the economy.

Others are not convinced.

At a conference fringe meeting today former SNP MP George Kerevan won warm applause after arguing the commission was too "conservative" if it did not provide hope for the poor and unemployed.

The discussion on that will continue in a party that, in recent times at least, has not had much in the way of contested policy debate.

But there are bigger problems ahead.

Ms Sturgeon has said she will decide in the autumn whether to demand a second referendum when there is a clearer picture on Brexit.

Given recent events - with a divided UK cabinet exposing its differences in public - some might argue that even by the autumn there may not be much Brexit clarity.

And if there is continued uncertainty that might give Ms Sturgeon the reason she needs (excuse her opponents might say) to put off the referendum.

However, if she does conclude there is a clear picture, or clearer, then she will have to make the biggest political decision of her political career.

Like her party activists she wants to hold another referendum. She longs for one. Independence is what she lives for.

But she will also be aware that the polling at the moment - from NatCen and others - shows support for independence is stuck at around 45% with support for the UK at about 55%.

That's where it was at the time of the 2014 referendum.

Now, there are some nationalists who argue that support for the cause is way ahead of what it was at the start of the first referendum and they can win from 45%, others are not so sure.

But even though they may not admit it in public, nagging away in the back of party strategists minds must be the thought that perhaps they are stuck, that support for independence will not rise.

If that is the case, or if that is a possibility, would Ms Sturgeon demand indyref2 knowing she might lose, something that could set back the cause for decades?

Finally, there is the further problem of whether a referendum will even take place if Ms Sturgeon demands one.

Legally a second referendum has to be sanctioned by Westminster, as the first one was, under what has been called the 'Edinburgh Agreement'.

But all the indications are that Westminster will simply say 'no'. Theresa May recently repeated the mantra that "now is not the time".

But sources I have spoken to in Westminster say that actually means 'no'.

Scottish Tory leader Ruth Davidson told me as much recently, saying that it would not happen in the lifetime of this Scottish parliament which runs to 2021.

So if Ms Sturgeon does decide to call for another referendum - and her activists may trust her on timing but they want it to happen soon - what does the First Minister do when the woman in No 10 says 'no'.

Ms Sturgeon has said she wants the Edinburgh Agreement process to happen again, and not "do a Catalonia' - holding a referendum that would be illegal, however galling that is to Nationalists who believe sovereignty rests with the Scottish people, not Westminster.

It appears the First Minister is relying on pubic opinion turning her way, that support for the idea of independence will increase and the Prime Minister will be unable to resist the clamour for indyref2.

Which brings us back to that poll on the voters' views on the economic benefits of independence.

If Scots are losing their reservations on the economy, then the SNP hope they can be persuaded to back the idea of breaking with the UK.

In the SNP's view they'd be stupid not to. Though they wouldn't put it quite like that, of course.