But during periods of low unemployment, tax cuts can actually be damaging to the economy. If companies find it difficult to respond to the additional demand for goods and services by hiring workers and increasing output, the result is likely to be higher prices rather than faster economic growth.

The unemployment rate fell to 4.4 percent in April, a low level that most economists regard as the normal churn of people moving among jobs. Some economists argue that stronger growth could persuade more people to start looking for work. But that debate is academic because the Federal Reserve is in the first camp. Fed officials have said that if fiscal policy makers step on the gas by cutting taxes, the Fed is likely to step on the brakes by raising interest rates more quickly.

Mr. Trump’s plan also would significantly increase annual federal deficits, adding trillions of dollars to the federal debt. Increased government borrowing drives up interest rates and reduces the financing available to the private sector, both of which weigh on economic growth. An analysis by the Urban-Brookings Tax Policy Center of Mr. Trump’s campaign tax plan — which closely resembles the current White House plan — projected that the net result would be slower growth.

“I think well-designed tax reform could add to economic growth” in the long term, said Jason Furman, a fellow at the Peterson Institute for International Economics who served as chairman of President Barack Obama’s Council of Economic Advisers. “But poorly designed, deficit-increasing tax reforms are as likely to reduce growth as they are to add to growth.”

Economists see little short-term benefit in a tax cut, but they think the government could strengthen long-term growth by focusing on the right problem: productivity.

The speed limit on economic growth depends how much more every American worker produces. The Fed estimates the economy can expand at a sustainable pace of around 1.8 percent a year — close to the actual pace since 2010.