President Trump on Wednesday plans to target his pitch for tax cuts to what the White House sees as a key constituency: the nation’s truckers.

Trump is scheduled to deliver a late-afternoon speech in Harrisburg, Pa., where he will tout the Republican tax plan with an emphasis on the benefits for those who navigate the country’s highways, whom he will dub “the lifeblood of our economy.”

“Nothing gets done in America without the hard-working men and women of the trucking industry,” Trump plans to say in his speech, according to a senior administration official. “America depends on you for the fuel that powers our cars, the produce that nourishes our communities and the beautiful steel that stands up our tallest skyscrapers.”

The speech will be attended by hundreds of truckers, as well as Pennsylvania business leaders, the administration official said, who spoke to reporters on a conference call on the condition of anonymity to preview the speech.

During the address, scheduled in an airport hangar with trucks on site as props, Trump is also expected to tout a provision of the plan, outlined in a nine-page paper in late August, that would provide a special one-time tax holiday for U.S. companies willing to repatriate funds from abroad.

“We will eliminate the penalty on returning future earnings back to the United States, and we will impose a one-time low tax on money currently parked overseas so it can be brought back home to America where it belongs," Trump is prepared to say in the speech, according to the senior administration official. "My council of economic advisers estimates this change alone will likely give the typical American household a $4,000 pay raise."

Neither that official nor other White House aides would provide any detail Tuesday on the math behind the $4,000 figure, including the time span for the purported savings. One aide said a white paper on the subject would be coming shortly.

Kevin Hassett, the economist who chairs Trump’s council, cited the figure in a speech last week in which he talked about what would happen if U.S. companies no longer left their foreign earnings offshore.

“In 2016, U.S. firms kept 71 percent of foreign-earned profits abroad,” he said. “What would happen if they didn't do that? A simple back-of-the envelope calculation suggests U.S. workers in 2016 would have received a raise of nearly 1 percent. What if these firms didn't do that for the next 8 years? The median U.S. household would get a $4,000 real income raise.”

A similar repatriation effort in 2004 provided little in the way of hiring, and some of the companies that benefited from the tax break actually cut payrolls. Several studies have concluded the benefits of the effort fell far short of what was advertised.

The administration official who spoke with reporters said Trump’s plan would benefit truckers in several ways, including a lower top marginal rate for small businesses that file as “pass-through entities.” Another GOP provision, the repeal of the estate tax, would benefit family-owned companies that pass along assets to the next generation, the official said. And, the official said, lower taxes on manufacturers will stimulate growth and raise demand for trucking.

During the speech, Trump plans to point to several taxpayers in the audience, including truckers, who would benefit from his plans, the administration official said.

Trump has previously pitched his tax plan in  three other states with vulnerable Senate Democrats up for reelection: Missouri, North Dakota and Indiana.

Sen. Bob Casey (Pa.), a member of the Finance Committee, is one of 10 Democrats in the chamber who are up for reelection next year in states that Trump won last year. Casey is not expected to attend the event.