On the face of it a Conservative-SNP deal looks very unlikely. A coalition is definitely not going to happen, but the chances of a confidence and supply arrangement is not totally unthinkable.
In Alex Salmond’s minority administration, in Holyrood, between 2007 and 2011 the SNP relied heavily on Annabel Goldie’s Scottish Conservatives for support, especially for annual budgets. The two parties have worked together in the past so it’s at least possible that they could do so again.
But would they really? Perhaps if the Conservatives offered to transfer substantial powers to Scotland from London then a deal could be plausible, but could such a deal ever happen in this climate?
Probably not. In Scotland the Conservatives are seen as a toxic brand to many. In 1997 they lost all their seats north of the border and in terms of their shares of the vote in subsequent general elections they have failed to achieve an increase. For SNP supporters, a deal with David Cameron’s Conservatives, who currently lead the Westminster establishment that the SNP so hate, would be completely toxic. In practical terms such a deal could work but the backlash from SNP supporters could potentially be fatal for the party, especially since the party is embracing a social democratic agenda and voices opposition to Conservative-led austerity agenda coming from Westminster.
Therefore such a deal will not happen unless some constitutional crisis forces such an arrangement. To the SNP, such a deal would be hypocritical, and to the Conservatives it would appear to be a betrayal to the union to work with a party intent upon breaking up the United Kingdom.
A Labour-SNP deal looks much more likely but a lot will depend on the arithmetic, as well as the fate of the Liberal Democrats. This year's election will be the most unpredictable one in decades.