Private-sector job creation was considerably less than expected in March, indicating that the labor market's improvements could begin stalling.
A joint report Wednesday from ADP and Moody's Analytics showed 158,000 new positions, well below economist expectations of 200,000.
The report serves as a precursor to Friday's nonfarm payrolls report, so the miss could cause economists to lower their projections.
"I'm very optimistic about the economy but I think the next six months are going to be pretty tricky and we're going to see that in the job market," Moody's economist Mark Zandi told CNBC. "So I think we actually will see weaker jobs numbers in the next few months."
Zandi said the downturn in the March numbers came largely because construction rebuilding jobs that had been created due to October's superstorm Sandy began to fade.
Much of the job creation came from small businesses of less than 50 employees, which added 74,000 positions, while large companies added 47,000 and medium-sized firms hired 37,000.
Markets reacted little to the report, with stock futures still indicating a flat to slightly lower open.
As has been the case throughout the economic recovery, the service sector led the recovery in jobs, adding 151,000.
Goods-producing jobs hit a six-month low of 7,000, while there were no net job gains in construction following an average of 29,000 over the past three months. Manufacturing picked up 6,000 positions.
ADP also revised its February jobs count higher, from 198,000 to 237,000, while January's number came down from 215,000 to 177,000.