For nearly three years, the economy has been propelled by a single, but powerful force - consumers.
They snapped up cars, homes and electronic equipment at an astonishing pace.
But now, the mighty consumer appears to have hit the wall, his confidence shaken, his spending grown tenuous. Personal bankruptcies and credit-card debt are at record highs.
While economists agree that consumers are in a fragile state, many still believe they are not tapped out and will continue to carry the economy.
The economy "is still on the shoulders of the consumer," said Ken Goldstein, an economist at the Conference Board, a New York-based business research group. "Those are still pretty broad shoulders. They are bruised, but they are still pretty broad."
Added Milton Ezrati, senior economist and strategist at Lord, Abbett & Co., a money management firm in Jersey City, N.J. : "I think the consumer can contribute enough to keep the economy growing. It is not a question of whether we are going to grow with or without the consumer. Without the consumer there is no economy."
The economy, however, is showing signs of distress. Just 15 months after it emerged from recession, there is growing belief that the economy could slide back into one if the war in Iraq drags on.
Even without war worries, though, the economy is facing problems. Job growth has been anemic, unemployment is creeping up and is expected to continue rising, and corporations have been reluctant to spend money on new equipment and facilities.
More recently, consumers have shown signs of pulling back, especially on purchases of homes and cars - the very sales that recently fueled the economy.
In February, sales of new homes dropped 8.1 percent, the poorest showing since August 2000. In the same period, car sales dipped 1.5 percent after a 9.9 percent increase in January; and factory orders for big-ticket goods, such as refrigerators, computers and washing machines, fell 1.5 percent after a 1.7 percent gain the prior month.
Many economists blame the poor results on the huge snowstorm that hit the East Coast over the Presidents Day weekend, which kept consumers out of malls and stores.
More worrisome, though, is consumer confidence, which soared three years ago as the stock market peaked, but plunged last month to its lowest level since October 1993, when the economy was recovering from the 1991 recession.
"I think it is fairly clear that consumers are turning cautious," said Scott Hoyt, director of consumer economics at Economy.com in West Chester, Pa. "They are worried about the war ... they are worried about the labor market. That affects jobs, that affects incomes."
Despite the cracks, economists say, consumers have enough left in their wallets to keep the economy moving ahead - at a slow pace.
The reason: Personal income is rising at an annual rate of about 3 percent.
"If income is rising ... it is at least some money to afford them some increase in spending," said Goldstein, the Conference Board economist. "There is a chance that consumers can continue to hang in there. We certainly know they are not tapped out."
Real per capita disposable personal income - total after-tax income - rose to $24,791 per person in January, up 2.8 percent from a year ago, according to Economy.com.
"It should keep rising," Hoyt said. "The only reason it wouldn't is if the war turned ugly and the economy dipped into recession."
Another reason for optimism, economists say, is that 94 percent of Americans are working and bringing home a paycheck. In addition, interest rates are low and another tax cut would put more money in consumers' pockets.
"The issue now is the willingness to spend," said Gary D. Keith, regional economist at M&T Bank Corp. of Buffalo, N.Y. "There are fundamentals that say the consumer is in good shape."
Consumers, however, binged on homes and cars.
More than 68 percent of American households own homes, a 6 percent increase over the past 10 years. Their outstanding home mortgage debt shot to $6 trillion last year, up $668 billion, or 12.4 percent from a year earlier, according to the Federal Reserve Board.
Consumers also tapped their houses for $212.4 billion in home equity loans last year, a 37 percent increase from the prior year, according to the Fed.
That has resulted in heavy debt loads.
The percentage of disposable income on average required to make minimum debt payments totaled 13.97 percent in last year's fourth quarter, according to Economy.com. Although that's a high level, it was down from 14.41 percent a year earlier.
"The level of debt in dollar terms relative to income, even relative to consumer net worth, is very large," said Ezrati, the economist and strategist at Lord, Abbett & Co. "The outstanding amount of debt makes the consumer more fragile than in the past."
But Ezrati does not expect a surge in loan delinquencies. He said many consumers locked in at low interest rates and shouldn't have a problem making payments.