WASHINGTON, Sept. 12 — The American economy finally seems poised to roar ahead at rates not seen since the late 1990's, but economists and some political analysts say the surge may not help President Bush's re-election campaign next year.

A wide range of data suggests that the economy will probably grow at an annual rate of nearly 5 percent in the final months of this year and nearly 4 percent next year — rates that would normally be spectacular news for an incumbent president.

But in a disparity with no real parallels in the last half-century, most economists predict that unemployment will remain almost unchanged at nearly 6 percent through the elections in November 2004.

The incongruous pattern of rapid growth with a stagnant job market stems primarily from an extraordinary gain in productivity, which has allowed companies to produce far more goods with far fewer people. Industrial production has jumped 5 percent since the last recession ended in late 2001, but companies have eliminated one million jobs over the same period.

The political fallout could be bigger than even the job statistics suggest, because most of the job losses have been in manufacturing, a significant sector for many of the most important swing states in the next election: Pennsylvania, Ohio, Michigan, Missouri and Illinois.

White House officials are keenly aware of the problem. In the last six weeks, Mr. Bush has traveled to Missouri twice and to Pennsylvania and Indiana to talk about his plans for creating jobs.

Acting on complaints from manufacturers that China has been manipulating its exchange rates to compete unfairly, Treasury Secretary John W. Snow openly urged the Chinese government this month to adopt flexible rates. Beijing agreed, but it rejected calls to move quickly in that direction.

Political analysts say voters need to feel for themselves that the economy is improving and that they need to start feeling that way by sometime next summer. Economists, meanwhile, worry that the economy could slow if employment does not pick up by sometime next spring.

"It is almost a race against time," said Nariman Behravesh, chief economist at Global Insight, an economic forecasting company in Waltham, Mass. "The risk is that we continue to shed jobs over the next 13 or 14 months. It's not the mostly likely scenario, but I wouldn't rule it out."

And there are other timing issues. Even if statistics suggest the economy is red hot by early next year, it might take several more months for large numbers of voters to actually feel better about their prospects.

New data released today suggested that people are still nervous. Consumer confidence unexpectedly dropped slightly last month, according to the University of Michigan's latest monthly survey. And retail sales, which climbed rapidly this summer, rose only 0.6 percent last month, short of expectations.

"Public opinion and consumer confidence are lagging indicators because people need to feel the changes in their own lives," said Andrew Kohut, executive director of the Pew Research Center.

The persistent stagnation in jobs provokes obvious similarities to the "jobless recovery" that contributed mightily to the first President Bush's re-election defeat in 1992.

But the differences are significant. Back then, unemployment was running at 7.8 percent and the economy was growing slowly, a marked contrast to the explosive growth rates many economists are predicting.

The reason for the bleak outlook on jobs boils down to basic math. The number of new workers is climbing about 1 percent a year. If productivity increases by an annual rate of 3 percent — and the rate has been above 5 percent both this year and last — economic growth, as measured by gross domestic product, needs to be significantly more than 4 percent next year before there is drastic improvement in the unemployment rate.

"I don't see where the demand is going to come from to produce a falling unemployment rate," said J. Bradford DeLong, an economist at the University of California at Berkeley. "Very few people are predicting real G.D.P. growth of more than 4 percent."

White House officials dispute that prognosis. If productivity and growth are rising, they contend, then new jobs will follow.

"There is a very strong correlation between real G.D.P. growth and developments in the labor market," said N. Gregory Mankiw, chairman of the White House Council of Economic Advisers. "We will see employment picking up by the end of the year, and we will see very strong advances in employment in 2004."

By any measure, there is much evidence to suggest that the economy is about to grow more rapidly. Corporate profits have climbed much faster than expected over the last two quarters. Retail spending grew rapidly this summer, and many companies are suddenly scrambling to keep up with demand. Inventory levels have dropped to quite low levels, which usually means that companies have to increase production.

Business investment, which has been the weakest leg of the economy for some time, has picked up modestly. And the stock market has been buoyant, which is an indicator of optimism among investors and makes it easier for companies to raise money for expansion.

More than a few economists say that the economy might expand at an annual rate of more than 5 percent in the final half of this year. According to the most recent Blue Chip survey of economic forecasters, the consensus forecast is that growth next year will be nearly 4 percent.

But there are some red flags. John Makin, an economist at the American Enterprise Institute, said the economy could still sputter sometime next summer. Much of the current growth, he said, stems from the recent tax cuts and tax rebates. But the jolt of that extra money will fade by early next year.

"The issue is the fourth quarter of next year, and that is where I have a concern," Mr. Makin said. "Demand will still be at a high level, but it may not be growing."

Edward McKelvey, an economist at Goldman Sachs, predicted this week that growth would "fade significantly" over the course of next year and that unemployment would begin rising by the end of next year.

Jerry Jasinowski, president of the National Association of Manufacturers, predicted that growth would be even stronger than many forecasters expect, but he also cautioned that many industry executives were reluctant to expand their operations.

"Manufacturers still have doubts that growth is in their hands," he said. "They are still skeptical that they will get a strong recovery."

Continued job stagnation would be bad news for Mr. Bush. Mr. Kohut of the Pew Research Center said recent surveys showed voters placing far higher priority on economic concerns than on terrorism. And while Mr. Bush continues to receive high approval ratings for his handling of terrorism and national security, Mr. Kohut said, his ratings on economic issues have fallen.