Hiring by U.S. companies stumbled to its slowest pace since the spring, payroll firm
The private sector added 154,000 net new jobs, down from 175,000 in August and below analyst expectations.
September's figure was the lowest since April.
The data indicate that Friday's more comprehensive jobs report from the Labor Department could be disappointing as Federal Reserve officials look for confirmation that economy is strong enough for another interest rate hike.
Mark Zandi, chief economist at Moody's Analytics, which assists ADP in preparing its report, said the labor market remained healthy and job gains would be expected to slow at this point in the long recovery from the Great Recession.
"With job openings at all-time highs and layoffs near all-time lows, the job market remains in full swing," said Mark Zandi, chief economist at Moody's Analytics, which assists ADP in preparing the report.
"Job growth has moderated in recent months, but only because the economy is finally returning to full-employment," he said.
Construction hiring rebounded in September, with companies adding 11,000 net new positions after shedding 2,000 the previous month.
But the hard-hit manufacturing sector continued to struggle in the face of a strong dollar that has hurt U.S. exports. The industry reduced payrolls by 6,000 in September, the seventh time in eight months that factories shed jobs.
Manufacturers had cut 4,000 net jobs in August.
Hiring also slowed last month in professional and business services, financial activities and the trade, transportation and utility sectors.
Analysts expect Friday's Labor Department report, which covers private-sector and government hiring, will show the economy added 168,000 net new jobs. That would be an increase from August's 151,000 figure.
Fed Chairwoman Janet L. Yellen said last month that central bank policymakers were likely to enact another small increase in a key interest rate this year "if we continue on the current course of labor market improvement and there are no new major risks that develop" in the economy.