For weeks the Conservatives have been running an attack campaign based on the possibility of Labour doing a post-election deal with the SNP. Their hope is to terrify English voters into voting Tory and, seemingly, to drive Scots further into the arms of the nationalists (who threaten to deprive Labour of almost all of their 40 seats north of the border). Ed Miliband last week ruled out a coalition with the SNP but his (wise) decision to leave open the possibility of a confidence and supply arrangement means that the attacks have continued.
The possibility – and even probability – that the nationalists could hold the balance of power in a hung parliament (with Labour and the Tories being unable to achieve a majority with Lib Dem support alone) explains why Miliband stands prepared to co-operate with the SNP. To do otherwise would be to severely weaken his chances of becoming prime minister.
But what of the Tories’ stance? Although the SNP have repeatedly vowed not to prop up a Conservative-led government they have not yet pledged to vote down any Queen’s Speech tabled by David Cameron (creating the possibility that they could abstain). Aware that the Tories will almost certainly be denied a majority (most post-Budget polls show Labour ahead), commentators such as Paul Goodman and Alex Massie have begun to speculate about the possibility of Cameron and Alex Salmond working together (as the Tories and the SNP did at Holyrood from 2007-11).
They note, as one Conservative MP did privately to me, that the party may be prepared to offer Scotland full fiscal autonomy in return for the SNP not voting down a Conservative-led government. Many Tories have long believed that forcing Scotland to raise as much as it spends is the best means of reviving the centre-right north of the border, with statist social democrats challenged by low-tax Conservatives.
All of which poses the question that Cameron and the Tories are currently firing at Miliband: do they rule out working with the SNP? If the Prime Minister refuses to do so, it will be clear that he is making the very political calculations that he has condemned Labour for.