This puzzles many of those who remember the poster stuck in Bill Clinton's campaign room during the 1992 presidential election to remind his team of their priorities: "It's the economy, stupid". It certainly puzzles most Conservatives, who fail to understand why they are not being rewarded for the state of the economy.
In fact, there are two puzzles. The first is why, if the economy is so important, the Conservatives managed to win in 1992 despite the state of the economy which was then in the depths of the recession. The second puzzle is why support for the Conservatives has not increased as the economy has recovered. Answering the first helps explain the second.
The first part of the answer is to understand, as David Sanders of the University of Essex has shown, that what counts in the end is not the objective economy (what is happening) but the subjective economy (what people think is happening). The two are closely linked - if the economy is going down the pan then people are more likely to think that it is - but there can, of course, be a divergence between perception and reality.
This subjective economy has become known as the "feel-good factor", but Sanders showed that what actually mattered most was whether people thought they were going to feel better in the coming year, not whether they felt good at the present: the am-I-going-to-feel-good? factor is more important than the I-feel- good-now factor.
Sanders earned plaudits by correctly predicting the result of the last election some 18 months in advance on the basis of his model. This, then, helps explain the first of the puzzles. In 1992 the economy was in dire straits, but people thought that things were going to improve.
By April 1992, according to Gallup, those who thought that their own family's circumstances were going to get better in the next 12 months outnumbered by some 16 percentage points those who thought they would get worse. This aggregate personal economic expectations score - as psephologists choose to call it - was at the highest it had been since the general election before, in 1987. Expectations of future economic success, then, helped to deliver electoral success to the Conservatives.
However, there were three supporting conditions which enabled this to occur. First, in 1992 the electorate did not blame the Major government for the recession. People blamed, in roughly equal proportions, either the world economic situation or the Thatcher government (made up, of course, of almost exactly the same people as the Major government, but clearly perceived as different). In April 1992, just four per cent of people blamed the Major government for the recession.
Second, when asked by the pollsters which party they thought was best able to handle Britain's economic problems, voters put the Conservatives clearly ahead of Labour. By the end of the campaign they led Labour on this question by over 20 points.
And third, people were pessimistic about what might happen under Labour. When asked whether they thought they would be better-off under Labour, more people thought that they and their family would be worse off than better. So, in 1992, despite the recession, for which the government received little or no blame, people expected a better future, were more likely to trust the Conservatives to deliver that future, and worried that it would not happen under Labour.
Now consider 1997. The first clue to the Government's problems lies in people's expectations. Despite the 1992 election being fought in a recession, and this one being fought during a "boom", aggregate personal economic expectations - as measured by the Gallup 9000 polls - are at present lower than they were in April 1992, and are in fact still negative: that is, more people expect their family's economic situation to worsen in the next 12 months than expect it to improve. This might be because people do not believe many of the claims made by the Government. Last year Gallup asked people whether they believed three factual statements about the economy's performance. Each was true, but the percentage of people who said they believed each statement never rose above a third.
That said, economic perceptions have been steadily improving over the last three years, and by the date of the election they could well be positive. This could, then, be translated into electoral success for the Conservatives.
But so far there are no signs that this will happen. The public's expectations of their economic prospects may have increased from their nadir in April 1994, but there has been no accompanying rise in support for the Government. What appears to have happened is that the three supporting conditions that enabled the prospects of economic success to equate to Conservative electoral success have gone.
People do not now believe that they will be worse off under Labour. Indeed, it is now quite the reverse: more people think they will be better-off than worse off, with the plurality - a large chunk, averaging around 38 per cent - believing it will make no difference. The latest Gallup poll shows that only 26 per cent of the public think they will be worse off under Labour, whereas in 1992 this group accounted for around 37 per cent of the electorate.
Clearly connected with this, Labour is now seen as more competent to run the economy. For years Gallup has asked the following question: "With Britain in economic difficulties, which party do you think will handle the problem best - the Conservatives under X or Labour under Y?" And for years the Conservatives have led, usually by a wide margin. Labour now leads, and clearly so, by an average over the last year of some 16 percentage points.
And third, not having blamed the Conservatives for the recession at the last election, the public seems not inclined to thank them for the recovery this time. Last month NOP found that the Conservatives got nearly all the blame from those who thought that the British economy was doing badly but credit from less than a third of those who thought that it was doing well. In total, just 15 per cent of people give the Government any credit for the economy's performance.
If the Conservatives were going to win this election on the basis of the economy, they would need, as Frank Sinatra once said, to start spreading the news. But they also need to start spreading some fear. And, last, they need to start praying that the electorate will trust them and thank them. At present, the public show little inclination to do either.
The writer teaches politics at the University of Hull