But, the magazine says, Labour "lost ground heavily during both the 1997 and 2001 elections," with its average poll rating falling off by 5 points (most of the gains went to the Liberal Democrats, but the Tories gained in 1997 too).

And, the Economist reports, even polling figures aren't necessarily reliable measures, since they have been "seriously astray" as recently as 1992. "On average," the magazine reported, "the final polls put Labour narrowly ahead." Polling errors in subsequent elections were similar.

Still, none of these factors "mattered in the last two elections because Labour entered the campaign with such overwhelming odds," said the magazine, noting that in 1997, Labour led in the polls by 24 points, and again by 20 points in 2001. Now, as Blair is expected to announce his re-election bid, however, his party is up only 5 points, according to polls surveyed by the Economist.

"So, if history were to repeat itself ... Labour's poll lead would disappear by May 5," the magazine concluded, leaving Blair trailing the Tory candidate, Michael Howard.

Editor's note: