Now that the SNP has won the general election in Scotland, talk is understandably turning to the party's role in the new Parliament.
The SNP is keen to play up its potential for "holding Westminster's feet to the fire" but Labour has ruled out a coalition with the Nationalists.
Speaking at a public event in Yorkshire on Monday, Ed Miliband insisted: "It will not happen. There are big differences between us. Labour will not go into coalition government with the SNP. There will be no SNP ministers in any government I lead."
That sounds pretty definitive, doesn't it? Ah but wait... He rules out a coalition but neither Labour nor the SNP was ever going to agree to that. He might as well have dispelled concerns that he was about to embark on a BDSM-themed ménage à trois with Iain Duncan Smith and Moira Stuart.
The more likely arrangement was always a confidence and supply deal - where the Nationalists agreed to vote for Labour Budgets and against motions of no confidence - or a more unstable vote-by-vote set-up, like the informal arrangement which saw the Scottish Tories prop up the first minority SNP administration at Holyrood.
And Labour is making it known - through anonymous briefings - that it is open to a looser relationship with the Scottish Nationalists.
The Guardian's Patrick Wintour quotes a Labour source, who tells him: "David Cameron for his own electoral purposes is trying to suggest Scottish MPs should have no vote at Westminster and that is an extraordinary position for a Unionist politician to adopt."
David Cameron has repeatedly called on Labour to rule out any agreement with the SNP and the Conservatives have produced an election poster depicting Ed Miliband in Alex Salmond's pocket.
This is smart politics for the Tories for two reasons. First, it scares Middle England with the prospect of a weak Labour government beholden to Scottish Nationalists. Second, with no single party likely to command a majority in the House of Commons after May, it boxes Mr Miliband into abjuring the support of a 50-seat bloc and thus making his path to Number Ten all but impassable.
And Labour's refusal to be bounced is smart politics too - on the face of it, at least. The party has been out of power for five years, hardly an eternity in the history of Labour but 40 years in desert for the current generation of Labour politicians. Labour people want a Labour government. They may not be prepared to sit side by side with Nationalists - Labour attitudes towards the SNP range from uneasy indifference to coruscating hatred - but they will not spurn their votes. Walking through the Aye lobby with Alex Salmond from time to time is a small price to pay for a return to the Treasury bench. Labour has not forgotten the painful lessons of the 1980s, the last time they chose purism over power.
But, as is increasingly the case for the party, there's a Scotland problem. While Labour is fighting the Tories south of the border, in Scotland they are up against the SNP, which is telling voters that they can bring down the Tories and ensure a left-leaning Labour government by voting Nationalist.
Labour has strained to fight this narrative. It has claimed that the largest party always forms the government, which isn't true but has the advantage of sounding right. It has warned that voting SNP will make a Conservative government more likely, a point that is more reasonable but would be better expressed as "Voting SNP makes a majority Labour government even less likely than it already is".
It is an indication of the dire straits Scottish Labour finds itself in that "Vote for the party you hate to keep out the party you really hate" is the strongest line in its rhetorical armoury. But it is the only trump card Labour has left to play.
Or it was until today. Ed Miliband's comments have undermined Jim Murphy's case for a Labour vote in Scotland. Mr Murphy will argue that it makes the choice starker for voters. But by ruling out a formal coalition while leaving the door open to a looser pact, Mr Miliband appears to vindicate the SNP's claim that Scots can vote for them and still get a Labour government. Think voters don't understand parliamentary pacts? Don't be so sure; they're smarter than the political class might imagine.
This tells us a few things about Mr Miliband. He has resigned himself to falling short of an outright majority in May. He has given up on Scotland. He is hungry for power and will do whatever it takes to achieve it. The last point is hardly revelatory - this is politics, after all - but this sort of ruthlessness is normally reserved for rival parties. The UK Labour leader is stepping on the necks of his Scottish MPs to get into Downing Street. Those who survive won't forgive or forget.
But there is a more immediate problem. The Tories now have yet another attack line against the hapless Labour leader: If even his own colleagues can't trust him, why would you?
Stephen Daisley is STV's digital political correspondent. You can contact him at email@example.com.