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."