New York ? Consumers’ renewed worries about job prospects led to a bigger-than-expected drop in confidence in August and provided more evidence of the fragility of the economic expansion.

The Consumer Confidence Index, which had been rising since April, dropped to 98.2 from a revised reading of 105.7 in July, according to a report Tuesday from The Conference Board, a private research group.

The reading was well below the 103.5 that analysts expected, and was the lowest since May, when it registered 93.1.

“The slowdown in job growth has curbed consumers’ confidence,” said Lynn Franco, director of The Conference Board’s Consumer Research Center. “The level of consumer optimism has fallen off and caution has returned. Until the job market and pace of hiring picks up, this cautious attitude will prevail.”

Economists closely track consumer confidence because consumer spending accounts for two-thirds of all U.S. economic activity.

But some economists were not deeply concerned about the dip in confidence.

Mark Vitner, an economist at Wachovia Securities, sees the latest snapshot of consumer sentiment as only a “bump in the road” and expects the index will rebound this month.

“Consumers still sense that the recovery is on track, and they are expressing their concerns on the lack of job growth,” he added.

Michael P. Niemira, chief economist at the International Council of Shopping Centers, believes that when taking the numbers in context with the big rise in consumer confidence levels in June and July, “they’re not as bad as they might appear.” Consumer confidence jumped to 102.8 in June from 93.1 in May.

On Wall Street, a late-session buying spree gave stocks a moderate lift as investors managed to shrug off the disappointing confidence report as well as on manufacturing.

The Dow Jones industrial average was up 51.40 to close at 10,173.92.