Dunkelberg added that small-business owners didn’t know for sure what their future tax liabilities and regulatory environment would look like.
The NFIB report comes on the heels of some economic reports that did not meet expectations, such as the Labor Department’s finding that the economy added only 69,000 jobs in May.
The Commerce Department has also revised its initial gross domestic product estimate down to 1.9 percent.
With all that in mind, the economy remains a central issue in this year’s presidential campaign, and Republicans have latched on to President Obama’s comment last week that the private sector was doing “fine.”
Obama was at the time comparing the private sector to the public sector, which has shed hundreds of thousands of jobs in recent years.
The NFIB index found that small-business owners were a bit more confident about the direction of the economy, though slightly more owners than not still expect conditions to get worse.
More small businesses also reported having job openings that were difficult to fill, with that measure at its highest point since 2008.
And while May saw a slight dip in the number of owners reporting higher nominal sales, NFIB said that they had been encouraged by those figures over the last few months.