David Cameron got it bang on when he said a "tax cut is for life, not just for Christmas". The simple fact is that a tax cut based on borrowed money which finances it is not a tax cut at all. In fact, it is a deferred tax rise. Because you don't just have to pay back the borrowed money, you have to pay interest on it too. The challenge for the Conservatives is to be able to explain this in two jargon-free sentences. And they have three days to think what those sentences might be.
As David Cameron quoted from one of my blog commenters (Martin Day) last week in a response to Gordon Brown (although there was a shocking failure to hat-tip :), any suggestions left here may well find their way into common parlance. You have been warned!