For the past couple of weeks that old nursery rhyme “the Grand Old Duke of York” has been going through my head.

He had, as we know, ten thousand men, whom he marched to the top of the hill before marching them down again. There’s been a version of the refrain floating around since the mid-17th century, a memorable proverb for futile action.

It came to mind on Friday morning when the First Minister told BBC Scotland that a soft Brexit would likely remove a second independence referendum from the proverbial table, and again yesterday when Nicola Sturgeon told Andrew Marr that she wasn’t bluffing.

Of the former statement one un-named SNP MP alluded to the nursery rhyme in speculating that Nationalist troops wouldn’t be happy that “having marched them up to the top of the hill”, Ms Sturgeon had signalled “a possible retreat”. The same day, however, the First Minister’s spokesperson reiterated that another referendum was still considered to be “highly likely”.

Now this might be viewed as mixed messages, but actually the Scottish Government is being relatively consistent with such studious ambiguity. The First Minister is simply keeping all her options open and ensuring that both wings of her party – impatient and cautious – have something to hold on to.

As the song says, “when they were up, they were up, and when they were down, they were down”, and when “they were only half-way up, they were neither up nor down”. Right now, with the UK Government’s negotiating position as yet undefined, being neither up nor down is a sensible position for the Scottish Government to occupy. As the Scottish Tory leader Ruth Davidson put it the other day, Ms Sturgeon is “keeping Scotland in limbo” and deliberately so.

At the same time the First Minister is belatedly trying to decouple a second independence referendum from Brexit. In her interview with Andrew Marr, for example, she made the point several times that the argument for independence is “much bigger than the European Union”, being more a question of why Scotland should continue to put up being shoved around by nasty Tories.

In doing so, Ms Sturgeon clearly has an eye on the 400,000 or so Yes voters who supported Leave last June. They’re an intriguing and presently disorientated group, and had the SNP persisted in presenting independence as a straightforward choice between the UK and the EU, then they’d have risked that group voting the wrong way in a second referendum.

A major feature of Scottish politics at the moment are the shifting allegiances among certain groups of voters, something that’s likely to continue in May’s local government elections. In other words, the SNP will continue to dominate – most likely taking control of Glasgow – Labour will continue to lose ground, the Conservative comeback will gain further momentum and the Liberal Democrats will maintain their irrelevance.

It also seems likely that far from being fought on “local” issues, the battle for control of Scotland’s 32 local authorities will take place on the basis of “national” issues, chiefly the prospect of another independence referendum and the SNP’s record after nearly a decade in devolved government. The Scottish Conservatives are particularly confident that this’ll help them win back council seats lost over the past few decades.

Internal polling and recent by-elections, particularly a couple in Aberdeenshire before Christmas, support that analysis. And while obviously a “Unionist alternative” argument will be harder to push in urban areas like Glasgow, the more fertile electoral territory will be in areas, like the north-east, where the Scottish Tories did well last May.

Scottish Labour, meanwhile, finds itself in a position the Conservatives remember all too well, i.e. in a spiral of decline. While there’s nothing implicitly wrong with the once-dominant party’s leadership, tactics or messaging, when a political movement has lost the right to be heard by a significant chunk of the electorate – as was the case with the Tories 20 years ago – it simply doesn’t make any difference.

Already hollowed out by the loss of 40 MPs in 2015 and 13 MSPs in 2016, losing dozens of councillors in 2017 will continue to diminish the Scottish Labour Party’s political capacity and motivation. Kezia Dugdale, meanwhile, is clearly conscious that her party is vulnerable to that national dimension in May, which is why she issued a “save the Union” rallying cry a few days ago.

But the trouble with that is it’s come too late. After the 2015 general election Scottish Labour made the mistake of trying to out-Nationalist the Nationalists, implying that in a future referendum the party would tolerate its candidates and activists campaigning for independence. Now Ms Dugdale says the Union is in grave peril, so it’s not just the First Minister who’s guilty of mixed messaging.

Responding to Ms Sturgeon’s Marr interview, for example, Ms Dugdale accused the SNP of sowing further “division and uncertainty” while repeating her call for a People’s Constitutional Convention and a new Act of Union to “save the Union” from being pulled “apart” by the SNP and Conservatives.

This coincided with reports that the UK Labour Party will call for “radical federalism” as an alternative to independence, which is both welcome and intellectually coherent, though likely to be a tough sell for the aforementioned reasons. The trouble is that the majority of voters have already made up their minds about both Ms Dugdale and Jeremy Corbyn, and even the best policy ideas won’t be enough to win them over.

On the bigger picture, meanwhile, for all the First Minister’s talk of “compromise” the Scottish and UK governments’ positions on Brexit remain irreconcilable: the former wants a quixotic arrangement by which Scotland can remain part of the single market, while the latter desires a bespoke arrangement with – but not membership of – the EU’s free-trade area.

That could end up vindicating the Scottish Government, but then there’s also the likely pattern of EU politics for the SNP to contend with. It’s all very well depicting the UK as in the grip of right-wing Brexiteers, but what about events on the Continent? By the end of 2017 EU Member States from Poland to France could be under the control of much more extreme administrations, rendering “independence in Europe” a rather less attractive option.

So the point remains that the SNP’s long constitutional dance is running out of floor space. When the party gathers for its spring conference in just over two months’ time the formal triggering of Article 50 will be just days away. At that point it’ll be crystal clear that the First Minister’s suggested compromise isn’t going to happen, and thus Ms Sturgeon will have to decide if she’s marching her troops to the top of the hill or back down again. Continuing to be neither up nor down is surely subject to the law of diminishing returns.