Private payrolls tumbled by 301,000 in January, posting their biggest drop-off since the onset of the pandemic, as the omicron variant set off a spike in coronavirus cases, according to data released Wednesday.

The unexpected findings by ADP — which had forecast a gain of 200,000 jobs for the month — represent the first time the payrolls processing firm has reported negative employment growth since December 2020 and the biggest decline in employment since spring 2020. They also cut against federal data showing more moderate losses. The wide variance suggests the labor market was more chaotic last month than previously thought.

The federal government will offer its own snapshot of the labor market on Friday, when it releases January jobs data. Though ADP’s estimates often differ, the shift it documented Wednesday — from a gain of 807,000 jobs one month, to a loss of 301,000 the next ― could reset expectations for the Labor Department’s report.

“The surge in Omicron is clearly slowing the job market,” tweeted Glassdoor senior economist Daniel Zhao, who called the ADP report a “negative indicator” for Friday’s jobs report.

Kathy Jones, the chief fixed income strategist for Charles Schwab, said the ADP data may be a precursor to a weak jobs report on Friday.

“The one thing to note is that all sectors are negative and the last time that happened was in April 2020,” Jones tweeted.

There’s already ample signs that hiring slowed leading into the new year.

More than 4 million people quit jobs in December, according to federal data released Tuesday, and more than 8 million missed work because they were sick or caring for someone who was sick from late December through early January. Roughly 247,000 Americans applied for unemployment insurance each week, according to the Labor Department, a significant uptick from November when the number of weekly claims dropped below 200,000.

One major reason for this is the omicron variant, which picked up enormous velocity in December, shuttering many businesses, schools and day-care centers and disrupting life for many Americans. Though its spread appears to have peaked, it still is causing more than 2,000 deaths per day.