The thing is, their attack lines of the last few days, the 'coalition of chaos' nonsense, of a lefty party being propped up by an even leftier party isn't even new. Back in early March, which seems like a foreign country already, Dave was mouthing off about a Labour/SNP deal. "You could end up with an alliance between the people who want to bankrupt Britain and the people who want to break up Britain", says the man waving £25bn worth of unfunded promises. However, the Tories think they're on to a winner this time. After spending time with focus groups (which is a problematic method for finding out what "real people" think), they've come to the conclusion that sufficient numbers of voters would be concerned if the SNP were to use their leverage to fleece the English taxpayer. If you put it to your focus groups in those terms, it's hardly shock, horror.
There is something to this though. Nationalism by its very nature is divisive. Our friend Nicola Sturgeon, for example, might hold to a nice civic nationalism in which anyone identifying as a Scot is welcome (in itself, not different from the contemporary recasting of British nationalism) but it still creates an in group and out group that pays no respect to the class underpinnings of social democratic/labourist politics, which the SNP have adopted with no small success. As the Scottish independence party, its 'other' is the multinational state that lays claim to majority of these isles. That implicitly means the majority shareholder of that construct: England. It's a politics whose vision of the good society is contingent on separating from us down in the warmer climes. Unsurprisingly, it feeds the deeply anxious beast that is English nationalism. The very idea of the SNP extracting special favours for Scottish budgets at the English taxpayers' expense is something the Tories are banking on. They talk up the SNP to stoke a resentful Englishness - never minding that they're imperilling the very union they profess to love. The main question, however, is will it get traction?
Undoubtedly it will get some sort of an echo. Those tending toward UKIP might be tempted. Voters who were in the habit of giving electoral time to the BNP by way of a protest too. Also layers of people who don't pay close attention to politics, but occasionally pick up a bit of messaging. Among those who have been softened up by years of propaganda against benefits cheats and immigrants, it addresses the interplay between hard-done-to taxpayer and workers-as-martyrs. It will niggle and nag at people, snap at their thoughts, and make them think twice about voting Labour or supporting UKIP. Is that really the case though? So far, painting Ed Miliband as the dolewaller's champion hasn't worked, nor have the dire warnings of economic catastrophe. Also, if you want to get into the scaremongering business, Labour has a much bigger weapon in the Tory record on the NHS than the blues have with constitutional jiggery pokery.
Nevertheless, to their credit the SNP and Labour both moved to quash this attack before Dave reheated it this week. In the leaders' debates Nicola Sturgeon has somewhat successfully detoxified English expectations of what the SNP are about. And for his part, Ed Miliband continues to rule out a coalition - it looks like his favoured approach, assuming Labour forms a minority administration, will be to forge his own policy agenda and dare the other parties to vote it down. There's no way, for example, the SNP would not support those recognisably social democratic aspects of Labour's programme, nor would the Tories say no to Trident replacement. Also, if the Tories want to play the narrow nationalist card they could lose as much as they gain. Their esteemed lordships Norman Tebbit and Micheal Forsyth are of this opinion, and it cedes crucial 'one nation' ground to Ed Miliband too - a point not lost on the Labour leader. And if they really want to throw in the nationalist card, UKIP can beat them at that game every time.
In all, there are not many more places the Tories can go. As Labour runs with the NHS this week and living standards the next, as their village idiot is embroiled in another scandal, time is running out for the Tories. And if they lose, their appalling campaign merely prefaces the death agonies to come.