The Business Roundtable's second-quarter survey, conducted before U.S. gross domestic product for the first quarter was revised down last month to show an annualized 0.7 percent contraction, found that CEOs expect 2.5 percent GDP growth this year.

That is down from the 2.8 percent growth expected in the last quarterly survey and 2.4 percent at the end of last year.

In the most recent survey, 70 percent of respondents said they expected sales to rise in the next six months, down from 80 percent in the first quarter, while 35 percent said they expected spending to increase over that period, down from 45 percent in the previous survey.

"Of particular concern is the downward movement of our CEOs' investment plans," said Randall Stephenson, chairman of the Business Roundtable and CEO of AT&T Inc. "Business investment is a key driver of economic expansion and job growth."

Stephenson said the U.S. Congress should enact tax reform and pass the Trade Promotion Authority, which would grant the president fast-track powers to negotiate trade agreements, in order to lift capital investment and boost the economy.

Thirty-four percent of CEOs said they expected to hire more workers over the next six months, down from 40 percent in the last quarterly survey.

The Business Roundtable CEO Economic Outlook Index, a composite index of expectations for the next six months for sales, capital spending and employment, fell to 81.3 from 90.8 in the first quarter. The long-term average of the index is 80.5.