The attack is two-pronged. First, it pushes the idea – contra Ed Balls – that cuts are necessary. And, second, it puts the Labour leader immediately on the back foot. Outside of government, the Tories would have deflected similar questions by saying that they hadn't yet seen the books. That excuse will be much harder to swallow from Labour leader who only had his hands prised off the books a few months ago.
What we are witnessing, no doubt, is the Treasury road-testing a new message on the deficit. Chuck in the argument that Nick Clegg made in his conference speech, and signs are that the government is set to be much more robust on this over coming months.