One of the first rules of election campaigns is that polls that secure the biggest headlines are not always the best guide. This is especially true when the headlines in question focus on the lead one party has over another, a figure that is especially vulnerable to fluctuation from poll to poll.
The YouGov poll in The Sunday Times suggesting that the Conservative lead was down to two points grabbed the headlines. But there was doubt about whether it might just represent random variation around the 5-6 point lead suggested by other recent polls. Now our latest ComRes poll, conducted over the weekend, indicates that the lead is indeed still five points.
That said, there is no doubt there has been a sea change in the parties' prospects over the past month. Until almost the end of January, the Tories consistently enjoyed a double-digit lead of around 12 points. Despite the unfavourable way in which the electoral system treats his party, that seemed sufficient to put David Cameron on course for an overall majority.
But then towards the end of January it was announced that Britain was out of recession. The initial 0.1 per cent growth figure, revised to 0.3 per cent last week, seems to have sparked off a gradual narrowing of the Tory lead. Immediately the Tories' average advantage slipped to nine points.
Subsequently, after Gordon Brown showed his softer side in a TV interview with Piers Morgan, the lead narrowed, to seven points, casting doubt on whether the Tories would necessarily win an overall majority, at least in the absence of an above-average performance in the key marginals.
The publication of Andrew Rawnsley's claims that Mr Brown sometimes behaves like a bully might have been expected to produce a setback. But as our poll confirms, whatever else they think of Mr Brown, most do not think he is a bully. Labour's progress has continued, and the lead now stands at five points. At that level the Conservatives have to do better in marginal seats just to ensure they are the largest party.
It appears the recession has helped to persuade people that Labour can indeed run the economy effectively. Our poll shows that people now have just as much confidence in Mr Brown's ability to restore Britain to economic health as they do in Mr Cameron's skill. Also, voters are seemingly looking at Mr Brown afresh. Our poll suggests that he is now regarded only a little less highly than Mr Cameron. Labour's task now is to reinforce these two new impressions.
John Curtice is professor of politics at Strathclyde University