So, Miliband won't do any sort of deal with the SNP even if that hands victory to the Tories. Way to go Ed, your party in Scotland is officially dead.
He knws he doesn't need an offiial deal.
The SNP's options are:
1) Vote yes to a Tory multi-coalition government with polar opposite ideologies.
2) Vote yes to a Labour minority (possible Labour-LD coalition) and block the 2) Tories, putting Miliband in #10
3)Vote no to Labour and Tories, forcing a re-election where the Tories will almost certainly do much better and the SNP can't possibly do any better (since they will win almost if not every seat).
4) Mosses' suggestion that they form some kind of coaliton with the Tories where the SNP gets devolution-max. But this is a deal with the devil, and the Tories are seen to help break up the union.
5) Remote chance the Tories and Labour form a grand coalition to ensure a stable government. It is irrelevant what SNP says.
Milliband is likely betting on outcome 2 because not saying yes to Labour is almost invariably worse for the SNP. I can't imaine 4 being a possibility, the SNP's will demand a referendum and a host of other thigns that the Tories just wont be willing to give in to just for the sake of being in power for 5 years. The Tories best bet is a re-election, they will have much higher odds of wining a second election, not least all the small parts will completely struggle
That is the point that some people don't seem to realize, Milliband doesn't have to say a word to the SNP but still indirectly will have the SNP on their side under most circumstances