The Federal Reserve is all but certain to cut interest rates this week even though the unemployment rate is at a historic low, a highly unusual action that is shaping up to be the biggest gamble of Fed Chair Jerome H. Powell’s brief tenure as leader of the world’s most powerful economic institution.

Many economists say the Fed is acting prudently to prolong the economic expansion, which this month became the longest in U.S. history. Yet the support is far from unanimous.

Some economists, Fed officials and people on Main Street say the move would benefit the stock market more than the real economy. And they argue that cutting rates would introduce risks that could worsen the next downturn.

Typically, when the Fed slashes interest rates, borrowing costs drop for mortgages, business loans, auto loans and credit cards, leading to more homes being sold, more businesses investing and more economic activity overall.

But loans are already cheap and few industries are asking for lower rates, suggesting that other factors outside the Fed’s control — a labor shortage, trade wars, a lack of housing supply — are limiting the economy’s potential.

“A Fed rate cut will have zero impact on the housing market,” said Tendayi Kapfidze, chief economist at Lending Tree. “Mortgage rates are already at three-year lows.”

Washington real estate agent Kara Sheehan agrees. She hears long wish lists from prospective buyers: urban homes with a parking spot or garage, a good price and houses that don’t need to be renovated. But they say little about mortgage rates.

“Buyers are a little more hesitant lately and very price conscious. They are all about property condition,” said Sheehan, of Washington Fine Properties.

The Fed’s actions this week, and the stage they would set for the rest of the year, would be the most significant of Powell’s 1½ -year tenure.

Powell, a low-key former private equity executive and think tank scholar, was a surprise pick to lead the world’s most important financial institution and has received praise from Republicans and Democrats for his stewardship of the central bank amid growing economic uncertainty and near daily tirades from President Trump.

Trump appointed Powell but has grown frustrated with the Fed leader’s approach, saying that he was wrong to increase interest rates last year and needs to be aggressive about cutting them now.

Powell and his colleagues at the central bank insist that they ignore Trump’s tweets and criticism and focus solely on keeping the economy growing, citing a global economic slowdown as a major reason for an interest-rate cut. They also say it’s better to cut now to prevent a recession than to wait for a downturn.

But by acting early, the Fed would introduce its own risks. Economic data released Friday showed that the economy slowed in the spring, but that it was still expanding at a healthy 2.1 percent.

If a downturn does occur, the Fed will have less room to maneuver in the future, and acting in the face of broadly healthy economic data risks making the Fed seem as though it’s caving to pressure from Trump or Wall Street. The Fed’s benchmark interest rate, which serves as a baseline for lending in much of the economy, is currently just shy of 2.5 percent, which is low by historical standards.

“These decisions aren’t just a pure slam dunk where it’s obvious what to do. These are difficult decisions in uncertain times,” said Donald Kohn, a former vice chair of the Fed.

The Fed’s likely course is a modest interest rate cut this week — a quarter-point — accompanied by signals stressing that the central bank will wait to see what unfolds before acting again, Kohn said.

But patience will be difficult with Wall Street already pricing in three cuts by the end of the year, and Trump’s top economic adviser, Larry Kudlow, saying the Fed should act, and “the sooner the better.”

The danger of acting too soon is that lower borrowing costs will spur even more risky lending that ultimately leads to a bubble bursting, similar to the dot-com era and the housing market crash. Corporate debt, much of it fueled by high-risk leveraged lending, is at a record high. Risky lending offers higher returns to investors, and can be in greater demand when interest rates are low in the economy.

“The Fed feels the need to come in and save the day like Superman, but all the Fed is going to do is encourage more corporate debt,” said Peter Boockvar, chief investment officer at Bleakley Advisory Group. “It’s not going to help, and then the Fed will keep cutting.”

For many economists, the argument against cutting rates is that the unemployment rate is sitting at a half-century low, inflation is mild and the economy is growing at a solid rate, a scenario that normally would not call for extra stimulus. Almost all of the economic data this month has surprised to the upside.

There’s wide expectation that several Fed leaders, including Boston Fed President Eric S. Rosengren and possibly Kansas City (Mo.) Fed President Esther L. George, would dissent on a rate cut this week, a reminder of how contentious the situation is.

But others argue that because the Fed has such little ammunition, it must be used early to try to prevent more difficult scenarios later on.

“When you only have so much stimulus at your disposal, it pays to act quickly to lower rates at the first signs of economic distress,” New York Fed President John C. Williams said in a recent speech.

Red flags in the economy are not hard to find, experts say. Trump’s trade war has spooked many corporate leaders, causing business investment to plunge, according to the latest Commerce Department report. Manufacturing, although only about 10 percent of the economy, was in a technical recession for the first half of the year, and conditions in Europe and China remain weak.

Consumer spending is holding up the U.S. economy, and that could falter if companies pull back on hiring in the same way they have on buying new equipment and buildings, economists say.

Powell also has emphasized repeatedly that many communities of color and Americans with criminal records have been able to get jobs lately, and how he does not want those gains to end.

Diane Swonk, chief economist at Grant Thornton, said: “We would have a much bigger problem if the Fed didn’t cut rates.”

In speeches, Fed leaders have been portraying this month’s likely decline in interest rates as an “insurance cut” that’s supposed to give the economy more breathing room, similar to loosening a belt after a heavy meal.

Swonk said the gains from a rate cut this week have been priced in. Powell began hinting in early June that the Fed was making what Swonk and others call the “Powell pivot” or the “Powell pirouette” to go from raising interest rates in 2018 to being on hold in early 2019 and now to signaling one or more rate cuts.

Investors reacted immediately, sending stocks higher and making lending conditions easier.

But the effect has been more muted on Main Street, another complication as the Fed tries to deduce the optimal path going forward.

Credit card borrowers are currently paying a record-high average interest rate of 17.76 percent, according to data compiled by CreditCards.com. In theory, that rate should decline as the Fed cuts the benchmark interest rate, but some analysts are skeptical that that would occur because of reasons outside the central bank’s control.

Credit card companies have become adept at increasing fees and finding ways to keep rates higher than the Fed rate would suggest, said Ted Rossman, an industry analyst at CreditCards.com.

“People with credit card debt shouldn’t view a Fed rate cut as a free lunch. They could well pay for it in other ways,” he said.

Similarly, auto sales surged in recent years, topping 17 million new vehicles a year from 2015 through 2018, and some auto analysts think that the nation has hit “peak car” and that there might not be many more Americans sitting on the sidelines waiting to buy, regardless of what loan rates are.

In the real estate market, the average 30-year mortgage rate dipped to 3.75 percent last week, the lowest since 2016, according to Freddie Mac.

Yet home sales remain sluggish and the median sale price in the United States — $310,400 — is almost exactly the same as it was a year ago despite much lower borrowing costs and even more Americans finding jobs.

“Some say they are a little concerned there is going to be a market correction, and that puts people in a cautious mode,” said Sheehan, the Realtor. “It feels like a good, but maybe not great, economy.”