The direct benefits of the tax cuts would mostly accrue to the wealthiest Americans, but Republicans say that increased investment will ultimately raise wages, too. Wage growth has remained sluggish in recent years even as the unemployment rate has declined.

Some economic forecasters have increased their estimates for economic growth next year, both as a result of underlying improvement in the economy and in anticipation of a significant tax cut.

The Organization for Economic Cooperation and Development said it expected the American economy to grow 2.5 percent next year, up from a forecast of 2.4 percent six months ago.

The potential pace of economic growth — the effective speed limit for the American economy — is determined by two factors: the expansion of the work force and the productivity of the average worker. Both have grown slowly in recent years, a trend that is expected to continue.

The government projected in October that the labor force would grow at an annual rate of 0.6 percent over the next decade. That is about half the pace of annual growth from 1996 to 2006, when the supply of workers expanded an average of 1.3 percent each year.

The slower growth of the work force reflects the aging of the population as the baby boom generation moves into retirement. The youngest members of that generation will be 62 by 2026. It also reflects the reduced volume of immigration. The number of people moving to the United States has declined in recent years, and the Trump administration is working to further reduce the volume of both legal and illegal immigration to the United States.

The reasons for the slow growth of productivity are less clear.

The productivity of the American economy — basically, the value of a given amount of work — increased at an annual rate of 0.4 percent from 2007 to 2016. That was about half the 0.9 percent pace of annual growth over the previous three decades.