The corporate aim of the SNP includes the party becoming the natural choice of all Scottish voters – thus occupying the dominant position that Fianna Fail did in Ireland for much of the post-war period.  To do this and win independence, it needs to eliminate both the Conservatives and Labour from Scottish Westminster seats, or at least make them minority concerns.  It has already done so to the Conservatives.  Now it is turning to Labour.

This is the point of Alex Salmond’s New Statesman interview today, in which he says that the SNP will vote against any Queen’s Speech which David Cameron puts forward.  As Salmond suggests, it follows that the party would also vote against a Conservative (or Conservative-led) Government in any no confidence vote.  He goes on to float a confidence and supply deal with Labour, or even a fully-fledged Labour/SNP Coalition.  But the details are less important than the message, which is: the SNP wants Ed Miliband as Prime Minister.

The interview is thus crafted to fit the SNP’s task of destroying Labour in Scotland at the coming election.  “Look,” Salmond is saying to natural Labour voters in the central belt.  “You can have the best of both worlds – a Labour Government in Westminster to keep out the Tories, and us in place there as the guardian of Scotland’s interests.”  Those Tory posters showing Miliband in his pocket are thus doing the SNP’s work in Scotland: Salmond might as well have sat down with Lynton Crosby and sketched them himself.

And if the consequence is that the Conservatives defeat Labour in England while the SNP defeats it in Scotland, so much the better for the party.  It will then have a Tory Government in place – the perfect backdrop against which to garner more support from voters for independence before Scotland’s own elections of 2016.  An SNP landslide, an English electorate weary of its demands (especially the Conservative and UKIP-voting bits of it), and a second independence referendum – at which Scotland would vote to leave.  Such is Nicola Sturgeon and Salmond’s game plan.

Her language has been more cautious than his, which may reflect tactical differences about the degree to which SNP should seek, at any given moment, either to prop up Labour at Westminster or simply cause chaos – maximising its own vantage and demonstrating its own strength in either event.  But the strategic direction is crystal-clear.  And like Miliband, Cameron doesn’t have a clue how to respond.  In this context, watching the current election campaign is like watching two rabbits paralysed by the approach of a weasel.

It may be too late to save the Union.  Almost everything has been tried – including denouncing the SNP, sending back the stone of Scone, devolution, and pretending the problem isn’t there.  Only three options are now imaginable for Scotland: the Union as it was, independence or federalism.  The first is gone.  That leaves federalism as the only Unionist option – Home Rule for all the Home Nations, as proposed in the ConservativeHome manifesto.  Part of such a settlement would of course be English Votes for English Needs (or laws, if your prefer): indeed, federalism offers the most likely route to it.

This site has never been hopeful that the SNP would accept what is, after all, the only remaining practicable route to securing the Union.  But we believe that Cameron should, as part of offering federalism to the people of Scotland, offer it to SNP MPs in the event of Parliament being hung six weeks from today.  As we put it on Monday, Cameron should seek to utilise “his First Mover Advantage as the serving Prime Minister…by coming to an arrangement with as many of the minor parties as he can…This, in turn, would mean striving to come to one with Alex Salmond.”

The New Statesman interview specifically puts the ConservativeHome idea to Salmond.  He has now given his answer.  Who knows what will actually happen if the Commons has no majority on May 8?  But Salmond appears to have gone much further than Sturgeon – and left Cameron wrestling with a paradox.

As a patriot, he wants to see the SNP lose ground in Scotland.  For this to happen, Labour needs to win seats off it come May 7, or at least hold his ground.  But as a politician, he wants to see himself back in Downing Street.  And that means the SNP winning seats off Labour – not vice-versa.  Salmond, Cameron’s strategic enemy, is also his tactical ally.