The U.S. job market slowed sharply in September, according to government data released Friday morning, raising new questions about the sturdiness of the country's economic expansion amid weaker growth around the globe.

The Labor Department reported that the United States added just 142,000 jobs in September, well below analysts' expectations. In addition, the government lowered its estimate of job growth in July and August by 59,000 positions. The unemployment rate has remained unchanged at 5.1 percent for the past two months.

The disappointing data come amid an increasingly gloomy global outlook. In the years following the Great Recession, emerging markets — led by China — supplied the strong demand and robust growth that helped cushion the slump in advanced economies. Now, China's breakneck pace is finally easing, with ripple effects that reach far beyond its borders.

"Today’s report does show the impact of slowing growth in Europe and China in U.S. job markets," said Andrew Chamberlain, chief economist at job site Glassdoor.com. “The global economy connects every place with every place else in some way. It’s just a question of how big are the effects?”

In a statement, the Obama administration used the jobs report to press lawmakers to find a compromise on two looming political battles with high stakes for the economy. Funding for the federal government will run out Dec. 11, while the Treasury Department said this week that lawmakers will need to raise the national borrowing limit by Nov. 5.

"Given the increased uncertainty around the world, it is imperative that the United States not further exacerbate that uncertainty with unnecessary brinksmanship and austerity," said Jason Furman, chairman of the Council of Economic Advisers.

In the United States, the job market had been growing at an average pace of more than 200,000 jobs a month since 2013, the level generally associated with a healthy economy. The hiring spree has helped bring the unemployment rate close to what many experts believe is its lowest sustainable level.

Indeed, the country's labor market has made significant strides since companies shed hundreds of thousands of workers amid the nation’s worst downturn since the Great Depression. The unemployment rate hit 10 percent at its peak in 2009. Millions of workers were out of a job for six months or more, and many were so discouraged about their prospects that they simply quit looking. On each of those measures, the job market is moving back to normal.

“This is a conversation about the pace of growth," Labor Secretary Thomas E. Perez said in an interview. "In many parts of the rest of the world, they want any growth.”

But a few areas remain concerning. The size of the nation's workforce slipped to 62.4 percent of the population, the lowest level since 1977. Demographic changes such as the retirement of baby boomers and an increase in the time spent in school have driven much of the decline, but economists hotly debate whether a stronger recovery might pull some workers back into the labor force.

Another critical area that has remained stagnant is wage growth, which has been stuck at about 2 percent for several years. September was no different: Average hourly earnings dipped by a penny to $25.09 and are up 2.2 percent from a year ago. That means that despite the recovery in the job market, many workers have yet to see a corresponding bump in their paychecks.

Meanwhile, the memory of the pain of the Great Recession is still fresh, and investors are on edge over any sign that the progress so far might be slipping away.

Several big-name companies have announced significant layoffs recently. Hewlett-Packard plans to slash 25,000 to 30,000 positions as part of a broad restructuring. Wal-Mart is anticipated to announce it will trim hundreds of positions at its headquarters in Bentonville, Ark., according to news reports. And the plunge in oil prices has forced U.S. energy companies to fire thousands of workers.

All told, companies announced 58,877 job cuts in September — a 43 percent jump from the previous month, according to consulting firm Challenger, Gray & Christmas. The number of layoffs so far this year has surpassed last year’s total, the firm said, and is on track to clock in at the highest level since 2009.

“We could see more fallout, which appears to have its origins in China, which after years of building up its national infrastructure appears to now have far too much capacity,” chief executive John Challenger said. “As a result, manufacturing plants, retail stores and even entire apartment building are sitting empty.”

Friday's job report showed that the mining industry shed 10,300 jobs, the largest decline of any sector and driven in part by the slowdown in fracking. The industry has lost about 100,000 workers over the past year. Manufacturing was also down by 9,000 positions as a stronger dollar has made U.S. exports less competitive.

"For manufacturers, these data reflect the sluggishness of the current activity, as firms struggle to overcome significant headwinds in the broader economy," said Chad Moutray, chief economist at the National Association of Manufacturers, a trade group.

China’s faster-than-anticipated slowdown has sent commodity prices plunging, roiling developing markets, such as Brazil, that have relied on exports to the world’s second largest economy to spur growth at home. This week, Christine Lagarde, managing director of the International Monetary Fund, warned that the agency plans to lower its expectations for global economic performance through next year.

Friday's data show that the United States is not completely immune. So far, the U.S. economy had proven relatively resilient, on track to grow at an annual rate of about 1.7 percent in the most recent quarter, according to an estimate from Macroeconomic Advisers. But Friday's jobs report is likely to raise some red flags.

The turmoil has been reflected in the volatility in financial markets. On Friday, U.S. stock markets opened sharply lower, falling more than 1 percent in the first 10 minutes of trading. This week also marked the end of the worst quarter for Wall Street since 2011, with the three major U.S. indexes all suffering corrections. A measure of financial market volatility spiked in August to the highest level in four years and has remained elevated ever since.

Adding to investors’ anxiety is the prospect of the first interest rate hike by the Federal Reserve in nearly a decade. The nation’s central bank slashed its benchmark rate to zero during the darkest days of the financial crisis in hopes of encouraging businesses and consumers to spend and bolster the public’s confidence.

The low rate, coupled with a massive stimulus effort that pumped trillions of dollars into the economy, helped bring down the cost of borrowing money for everything from cars to homes to factory equipment. As the economy improved, more people were able to get back to work.

Now, as the job market inches closer to a full recovery, the Federal Reserve is debating when to begin pulling back its support. Most of the central bank’s top officials believe it will raise its target rate by a quarter percentage point before the end of the year. But on Friday, some economists said the weak jobs report could cause them to wait until 2016.

"The mixed data support our expectation that the Fed will tilt to the side of caution during the process of policy normalization, implementing future rate hikes only at a very gradual pace," said Bob Hughes, senior research fellow at the American Institute for Economic Research.

Still, a top Fed official said this week that he expected to see job growth slow as the labor market improved: A smaller pool of unemployed people means less hiring is needed for the recovery to remain on track.

“The economy is on a solid footing and a good trajectory,” John Williams, president of the Federal Reserve Bank of San Francisco, said in a speech Thursday. “There are risks, as there always are in life. … But all in all, things are looking up.”