WASHINGTON (MarketWatch) — Fresh signs the U.S. economy has hit a soft patch have led economists to expect a disappointing May jobs report on Friday morning.

Economists polled by MarketWatch expect payroll growth decelerated to 125,000 jobs in May from a healthy 244,000 in April when the Labor Department releases data at 8:30 a.m. Eastern.

This would be the smallest increase since January and well below the three-month average of 233,000 job gains.

Just a few days ago, economists were expecting job growth of 175,000 jobs in the month, but a severely weak estimate of private-sector payrolls and a sharp drop in activity in the manufacturing sector led to a stampede of reduced estimates. Read ‘Economists rush to mark down payroll estimates’

Many economists blame the slowdown on a witches brew of temporary woes that hit the economy in this quarter.

Higher gasoline prices have cut consumer spending, analysts said. A lack of key parts from Japan due to the earthquake has had a negative impact on output. At the same time, deadly storms have ripped though many regions of the country, especially the Southeastern states.

The impact of the floods and tornadoes may become clearer when state unemployment data is released on June 17.

All-in-all, these factors have created a lot of uncertainty for businesses and they have responded by “tapping the brakes on hiring,” said Ryan Sweet, senior economist Moody’s Economy.com.

Sweet is forecasting a slim 80,000 advance in payrolls.

Indeed, a survey of business executives by the research firm The Corporate Executive Board EXBD found that hiring expectations dropped by 13 percentage points among U.S. executives in the first quarter. This was the first drop since the survey began in October 2009.

Michael Griffin, head of global research for CEB’s finance and strategy division, said executives were less confident in the strength of demand and were more worried about cost pressure arising from a pickup in input prices.

“For them, it is like running on a treadmill when both the incline and the speed go up,” Griffin said.

Josh Shapiro, chief economist at MFR Inc., said it is important to remember that it is longer-run issues that are making the economy vulnerable to temporary factors.

“If the economy were healthy on an underlying basis, these temporary factors wouldn’t be an issue,” he said.

Debt woes and a post-bubble housing mess have turned the economy into a “feeble old man” and not “a hulking linebacker,” he said.

Adolfo Laurenti, deputy chief economist at Mesirow Financial in Chicago, agreed that it seems facile to blame the slowdown in jobs on temporary factors.

“I am not sure that gasoline, earthquake and weather sum up the weakness we have seen in the economy in the past couple of weeks. It feels like something else is going on,” Laurenti said in an interview.

At this point, it may take severe weakness — or surprising strength— to catch the markets off guard after Wednesday’s stock market slide.

Scott Brown, chief economist at Raymond James & Associates Inc. in St. Petersburg, Fla., said the principal villain is higher gasoline prices.

“I think $4 a gallon really hit consumers hard,” Brown said.

Although prices have come down recently, Brown said the decline has so far been negligible.

The average price of a gallon on unleaded gasoline is now $3.78, down 20 cents over the past month, according to the motoring and leisure travel firm AAA.

“Demand starts to soften and businesses start to worry and are more reluctant to hire,” he said.

The job report will also have the latest data on average hourly earnings, which were up 1.9% on a year-over-year basis in April.

Economists expect a 0.2% monthly increase in earnings in May, which would keep the year-over-year rate steady.

This is just another sign that consumers do not have a lot of spare cash to spend.

Economists don’t see any pickup in wages with so much excess supply of labor.

The only wild card in Friday’s report that may be positive is the 62,000 workers hired by McDonald’s MCD, +0.37% in mid-April. Carl Riccadonna, an economist at Deutsche Bank, said the hiring by the hamburger chain should have an impact on the May payroll data.

A spokesman for McDonald’s said the company would not comment on the net number of jobs at the firm over the past two months

Laurenti said the jobs at McDonald’s do not have much impact on the economy.

“These are not the jobs for a family bread-winner with two kids,” he said.