Initially, Labour leader Ed Miliband simply ruled out what no one wanted, a formal coalition, while sensibly keeping his options open when it came to a more informal deal.
But events have moved quickly since then.
First, the SNP itself, or rather former leader Alex Salmond, appeared to distance itself from confidence and supply, speaking instead of an “issue by issue” arrangement.
Secondly, Labour has ended up having a better campaign than many expected, while some polls have predicted it to have the largest number of seats across the UK.
The result has been increased confidence when it comes to setting the terms of debate.
And lastly, last week’s SNP’s manifesto ended up echoing a lot of Labour commitments, for example a mansion tax, abolishing non-dom status and a bankers’ bonus tax – all largely cost-free pledges for the SNP but important in terms of positioning.
The upshot is that Labour has increasingly realised that if it emerges as the largest party at Westminster then it would be in a strong position to call the SNP’s bluff.
Importantly, Ed Miliband doesn’t need clear Nationalist support in order to become Prime Minister – that would only become important thereafter.
A crucial first test would be his queen’s speech, but it now looks possible for a minority Labour administration to draft something that the SNP couldn’t possibly refuse to support.
Trident, for example, could simply be left out and dealt with later on. The Liberal Democrats would also be more reliable partners.
Labour has always instinctively disliked the idea of relying upon SNP support in the Commons; after all, the Nationalists want to wipe them out in Scotland.
Ironically, however, events and SNP tactics have made it easier for Ed Miliband to contemplate forming a minority government after 7 May.
• David Torrance is a writer, journalist and broadcaster