Risk v change
Birmingham: "Time for a change" and "Don't risk it" are the two most powerful messages in politics. What makes the last week of this election so interesting is that both are embodied in the figure of Gordon Brown.
After 13 years, after the 10p tax fiasco, after the boom and the bust, after calling Mrs Duffy a "bigoted woman", he symbolises for many voters why it is time for a change. David Cameron clearly calculated last night that he could simply ignore the questions and the arguments posed by the prime minister, dismissing them as desperate stuff from a desperate man.
On the other hand, after weathering the economic storm, after helping to save the banks, after investing in schemes to keep unemployment and mortgage possessions lower than most people dared to hope for and after investing billions in schools, hospitals and tax credits, he also embodies Labour's warning against the risk of change.
Imagine if, say, David Miliband or Alan Johnson were now prime minister. While newness could significantly reduce the appeal of the "Time for change" message, neither would have the record or the reputation to allow them to say, with conviction, "Don't risk a change".
The battle is now on for the voters who switched to the Liberal Democrats after the first debate. The other two parties believe that Nick Clegg's appeal has been based on representing change and fairness. Therefore Labour's message is now that only a vote for it is a guarantee of fairness, given the risk of a Tory victory. Meanwhile, David Cameron's pitch is that only a Tory vote is a guarantee of change.
The question for next week is: can Nick Clegg persuade voters that Labour is finished and that the choice therefore is between a return to Tory rule and the new politics he claims to represent - or will he suffer a classic last-minute squeeze?
What a week it will be.