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How long before jobs number disappoints?

Forecasters look for job gains of 248,000 in March to be reported Friday, which would make it an eye-opening 13th month in a row above the 200,000 mark.

But this time, there are some questions about whether Wall Street is set up for a disappointment. Growth in the first quarter looks to have slowed to a crawl. Consumer spending registered its third straight monthly decline in February despite lower oil prices and strong job growth.

Job seekers fill out applications during a job fair in Princeton, Illinois, Jan. 5, 2015.
Daniel Acker | Bloomberg | Getty Images
Job seekers fill out applications during a job fair in Princeton, Illinois, Jan. 5, 2015.

Home building was anemic. Corporate profits have flatlined and business spending is as cold as the frigid weather that chilled many major Northeastern cities in February. In general, job growth simply can't outpace economic growth forever.

"I just don't think job gains at this level are sustainable unless we really have a very rapidly growing economy," said Ethan Harris, economist at Bank of America Merrill Lynch. "So yeah there probably will be some mild disappointment in jobs in the next six months or so.''

Indeed, private job growth decelerated in March. According to an ADP report released Wednesday, companies added 189,000 jobs in March, down from 214,000 in February. Economists had been expecting the number to be 225,000 jobs for March.

Still, Harris doesn't believe the disappointment comes this month with the Bureau of Labor Statistics report, and so he's sticking with his forecast of 270,000 for the March report.

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The bulls believe that business looked through what they believe is a weather-induced slowdown and kept hiring, like they did last winter. Jobless claims, they point out, have dropped below the 300,000 mark, an indicator of job growth of around 250,000.

"Job growth in particular is quite strong, and whether the number on Friday is above or below estimates, it really doesn't change the larger trend," said Dan Greenhaus, BTIG's chief global strategist.

Given the string of good jobs reports, it hasn't paid to be pessimistic. Over the past several months, economists have underestimated job growth, including a 200,000 undershoot in November.

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Mark Zandi, chief economist at Moody's Analytics, said payrolls usually follow growth from three to six months earlier, meaning the economy now is benefiting from the strong second and third quarters of 2014. But it also means that if the weakness continues, job growth could slow come the summer.

Economists will get an early signal from Wednesday's ADP report where the estimate is for private sector job growth of 225,000. Anything below 200,000, and questions will begin being asked if the jobs party is coming to an end and if weak economic growth in the first quarter has caught up with employment.

UPDATED: This story was updated to include the ADP jobs numbers.