Small and medium-sized companies are increasingly glum about the chances of a pickup in growth in the U.S. economy during the next year, a survey published today showed.

The percentage of chief executives of small companies who expect the economy to improve in the next 12 months dropped sharply to 31 percent from 50 percent last quarter, according to a survey by Vistage International, an executive coaching business, Reuters reported.

Dim expectations are keeping CEOs from expanding their long-term operations — 52 percent of those polled are holding back on permanent hires, though 49 percent said they would increase the total number of employees. That’s a drop from the 54 percent who said they would add workers in each of the previous two quarters.

Only 42 percent of businesses plan to invest in new plants and equipment, lower than last quarter’s 48 percent but above the 37 percent recorded in the second quarter of last year.

There was some good news for workers: 66 percent of CEOs said they planned to increase wages in the next 12 months. No comparisons are available for the previous period. Hourly earnings decreased in June for the first time in a year, according to the government’s non-farm payroll data released last week.

The survey comes hard on the heels of a surprisingly weak payrolls report that showed rising unemployment in June, and added to suspicions that the economic slowdown may not be temporary.

“We are seeing a pretty substantial reversal in confidence,” said Rafael Pastor, CEO of Vistage International. He said concerns over health-care costs, tight credit markets, slow progress on new trade agreements and anemic economic growth underlie the “growing frustration” among CEOs.

“They are seeing an economy that is going to stagnate, putter along,” he said.