The American economy added 173,000 jobs in August, a weaker showing than expected that makes it more likely the Federal Reserve will delay its long-awaited increase in interest rates when policy makers meet in two weeks.

But there was just enough positive data in the report on Friday from the Labor Department to keep a September move in play, even as Wall Street increasingly looks at the possibility of a Fed move in October, or at the central bank’s last meeting of the year, in December.

The report was hotly anticipated, mainly because it represents the last major piece of data that the central bank will have on hand before its meeting on Sept. 16 and 17.

Although hiring in August was well below the 220,000-job gain that economists had expected, the unemployment rate fell to 5.1 percent from 5.3 percent, the lowest since early 2008.

At that level, joblessness is nearing the level that economists and the Fed consider close to full employment, and inflation foes worry that an unemployment rate significantly less than that might result in an overheated economy in the long term.

That might seem strange to tens of millions of workers still looking for raises and full-time positions, but there are nascent signs that wages are finally beginning to tick higher. In contrast to the disappointing headline number, average hourly earnings rose by a better-than-expected 0.3 percentage point rate in August.

Payroll gains for June and July were revised upward by 44,000.

On balance, the report on Friday does not completely rule out a September rate increase, but it does strengthen the argument of more dovish officials who see little risk in keeping monetary policy accommodative and waiting until December to tighten it, or perhaps waiting for another month of data and acting at their October meeting.

Still, the report contained fodder for Fed hawks and doves alike, experts said. “The latest jobs data will leave everyone maintaining their position on the Fed,” said Steven Ricchiuto, chief economist at Mizuho Securities USA. “Not the decisive data the Street wanted.”

Federal Reserve officials have repeatedly signaled they plan to soon raise interest rates from near zero, where they have been since the depths of the financial crisis in late 2008.

But the exact timing of the decision has become an obsession for traders and investors on Wall Street, and something of a parlor game for economists and other armchair strategists, albeit one with billions of dollars at stake.

While the initial rate increase will be small — probably a quarter of a percentage point — it looms large psychologically for the markets because it will be the first increase in short-term rates by the Fed since June 2006.

Many Wall Streeters credit historically low interest rates and loose monetary policy for helping lift stock prices to near highs, and they worry that the inevitable tightening could put an end to the long post-recession bull market.

Some experts have been predicting a rate increase when the Fed meets in two weeks.

But another school of thought contends the Fed will wait until its last gathering of the year, in December, especially in light of the recent stock market sell-offs on bourses around the world.

Officials said at the last Fed meeting, in July, that they wanted to see “some further improvement” in labor markets. Stanley Fischer, the Fed’s vice chairman, said Saturday that the Fed was awaiting the results of the August survey to make that judgment.

Inflation remains sluggish, and a number of officials have expressed concern about the volatility of financial markets. They have said the central bank is unlikely to move until it can judge the reasons for the turmoil and assess the damage.

Eric Rosengren, president of the Federal Reserve Bank of Boston, said Tuesday that signs of a weaker global economy raised new doubts about the Fed’s expectation that domestic job growth would continue to be fast enough to drive up inflation.

“In my view, these developments might suggest a downward revision in the forecast that is large enough to raise concerns about whether further tightening of labor markets is likely,” Mr. Rosengren said.

The longer-term trend for job creation in 2015 has been fairly robust, even if wage gains have been disappointing. Before Friday’s report, the average monthly payroll gain since the start of the year stood at 211,000.

However, because of largely seasonal, not fundamental, factors, employment reports for August have a long history of coming in below expectations, only to be revised upward later by the Labor Department.

Over the last five years, according to Goldman Sachs, the government reported an average gain of 30,000 fewer jobs for the month than economists had expected. These August figures were ultimately revised upward by an average of 79,000.

Because of these shaky statistics, many economists say the bar is lower this time around, at least in terms of what constitutes a healthy labor market in the eyes of the Federal Reserve.

In all other months, a gain of less than 200,000 jobs might be considered lackluster at best, weak at worst, said Robin Anderson, senior economist with Principal Global Investors in Des Moines.

But given August’s history of big upward revisions, Fed officials and investors could likely take a more forgiving view of the data this report.

“The trend is so strong that one number alone won’t derail the Fed,” Ms. Anderson added. “These numbers are prone to revision, and you have to take the first estimate with a grain of salt.”