VLADIMIR Lenin said that there are decades where nothing happens, and there are weeks where decades happen.

Most of us would not generally find ourselves nodding our heads to Lenin, but in this quote he has described the last week in Scottish politics just perfectly.

This time last week, Kate Forbes had not confirmed her bid to lead the SNP, and Scotland. She was expected to enter, and she was expected to confirm that she was uneasy with the Gender Recognition Reform Bill, putting her on the side of the majority of middle-of-the-road people in Scotland.

Nobody expected this.

The received wisdom of journalists and commentators is that Ms Forbes is a busted flush, and indeed that may turn out to be true. On the other hand, if there are weeks when decades happen, just imagine for a moment how much can change during the five weeks of this leadership campaign.

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In many ways, the medium and long term appears easier to predict than the short term. And it is an interesting diversion from the SNP’s squabbles for us to consider the impact on the other side; the unionists.

Both the Tories and Labour are cock-a-hoop at the events of the last 10 days, barely able to contain their glee. There is a degree of logic in this. When we play out the options for the post-Nicola Sturgeon SNP, there is reason for unionism to be cheerful.

Adam Tomkins wrote on these pages, on Wednesday, that Ms Forbes was the candidate feared by his colleagues in unionism, and he is dead right. To be crude, 40 per cent of this country will vote Yes in any future independence referendum come what may, and a further 40% will vote No. In 2014, three-quarters of the remaining 20% voted No, largely because the nationalist case had insufficient economic credibility.

Humza Yousaf, now the firm favourite, has made clear that he is the continuity candidate of the urban left, continuing the coalition with the Greens which has, justifiably or otherwise, placed a dark cloud over the SNP’s reputation for economic seriousness. The continued narrowing of what it means to be a Scottish nationalist (leftism, centralism, Europeanism etc), instead of encouraging more of that 20% on board, will conversely only leave territory open for unionists to capture.

Ms Forbes, openly in favour of the concept of economic growth and generally much more economically centrist, and one would presume open to losing the Greens from government, would undoubtedly be well placed to encourage those soft unionists, with a tendency to favour creating wealth in order to then be in a position to redistribute it, to take a second look.

So, for sure, from the chaos of the SNP’s leadership contest comes unionist opportunity. But for whom?

Alas, not the Tories. Why any of my erstwhile colleagues in the Scottish Tory Party think this is their big moment is utterly beyond me. Confusion and delusion abound. It is now abundantly clear, to anyone who is able to emotionally disentangle themselves, that the Scottish Tories’ surge of the last six years was, as many of us said at the time, built on sand.

HeraldScotland: It's clear that the surge for Douglas Ross and the Scottish Tories has been built on sandIt's clear that the surge for Douglas Ross and the Scottish Tories has been built on sand (Image: Newsquest)

In truth the party’s core vote has always sat in the mid-teens, in percentage terms. It was there 20 years ago. It is there now. And it was there during the last two elections, when Labour voters backed the Tories because they felt they were in the best position to stop a second independence referendum.

Now that the Tories are heading out of power at Westminster, and Labour has a credible Prime Minister-in-waiting, those votes have gone straight back to Labour, like flicking the light switch from off to on. They were never Tory votes. They were unionist votes. The loan has now been repaid. And everything the Tories thought about themselves over the last six years has, predictably, evaporated.

Conversely, there is indeed good reason for Anas Sarwar’s Scottish Labour Party to have a spring in its step. In essence, for Labour to make its way into government in Scotland, and for Mr Sarwar to find himself waving from the steps of Bute House, there are two distinct voter markets into which he needs to tap in.

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The good news for Mr Sarwar is that one group has gone to him voluntarily – those unionists hitherto lending their votes to the Tories. However, he will find the other group to be a much stickier prospect. They are the soft nationalists who still think their wagon is better hitched to the SNP.

These are people who are generally not members of a political party. They are not the sort to make a banner and go on an independence march on a Saturday morning. They are not thirled to leaving the UK. Indeed, although they generally don’t love Britain, they do not necessarily want to leave it either.

However they are not likely to throw themselves into the arms of Mr Sarwar voluntarily, in the way the unionists have. They want significantly more power to be exercised closer to them. And they want to know that the Scottish Parliament is cemented into our constitution, and that it cannot be treated like a badly-behaved child by its Westminster parent.

They are for sale to the highest bidder, but if Mr Sarwar wants to be that highest bidder he must go to them, for they will not come to him.

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This is a critical time for Labour and Mr Sarwar. A serious offer on Scotland’s constitutional future (and for the avoidance of doubt, Gordon Brown’s recent proposals do not constitute that serious offer), coming at a time of uncertainty and discontent in the nationalist community over their independence strategy, could see Mr Sarwar accelerating towards a pot of gold at the end of the rainbow.

But this is no time for him to sit still and play safe. The SNP’s support is a glacier, melting very slowly without the direct intervention of boiling water. With elections just around the corner, Mr Sarwar needs to grab the kettle.