President Trump isn’t backing off his plan to slash tax rates for every American when he delivers a speech Wednesday aimed at mustering public support for a massive overhaul of the tax code, said White House officials, despite widespread resistance to tax cuts for the wealthy.

The speech in Springfield, Missouri, won’t include details of the administration’s plan, but will lay out Mr. Trump’s vision for a fairer tax system that benefits everybody, especially providing tax relief to boost workers, middle-class families and small business, the official said.

Will be leaving for Missouri soon for a speech on tax cuts and tax reform - so badly needed! — Donald J. Trump (@realDonaldTrump) August 30, 2017

“There has been this unfortunate idea that everything has to be zero sum and certain people have to lose for somebody else to gain,” said a White House official who spoke to reporters on condition of anonymity.

“We want a more optimistic vision of what real, sincere, genuine tax reform can do to improve the lives of so many Americans who have been shut out of economic opportunity and achieving their American Dream by bad economic policy,” the official said.

Seeking grass-roots support for his plan, Mr. Trump hopes, will put pressure on lawmakers to avoid the GOP infighting and Democratic obstruction that derailed the repeal of Obamacare.

The White House stressed that Mr. Trump is determined to deliver tax relief to Americans, but he also needs to put a legislative victory on the board to get his presidency back on track after the failure of the Obamacare repeal-and-replace bill.

The job of passing tax reform legislation got more complicated this week with the potentially unprecedented level of damage associated with Hurricane Harvey. Members of Congress will be debating emergency funding for hard-hit Houston and other areas as soon as they return in September.

Congress also must vote on raising the debt limit before the end of September.

The government has been bumping up against the nearly $20 trillion debt ceiling for months, and the Treasury Department has been using “extraordinary measures” to keep from breaching it. The department says it will run out of room by Sept. 29.

All these issues will underscore the impact of proposed tax cuts on deficits and debt that Mr. Trump and Republicans have promised to bring under control.

In the speech, the president will argue that lowering individual and business tax rates will jump-start the American economy and creating millions of new jobs.

Still, Mr. Trump’s anticipated rhetoric about fixing a “system rigged for the wealthy and special interests” will risk giving ammo to his opponents, including Senate Democrats who vow to block any plan that provides new tax cuts to the top 1 percent of earners.

“When you hear the president talking about ending the rigged system, I think another way to phrase that is restoring a fundamental American precept, which is fairness,” said another White House aide, also speaking on condition of anonymity.

“It is unfair that the wealthy and highly connected few who can afford an army of lobbyists, accountants and lawyers are getting special treatment in the tax code,” the aide said. “So ending the rigged system, a big part of that is restoring fairness by streamlining the tax code and closing those special interest tax deductions and loopholes, which ultimately is going to allow us to bring rates down for everybody.”

Capitol Hill Republicans have struggled to craft the tax reform legislation that accomplishes the goals they share with the president, including cutting taxes while not increasing deficits and debt.

The detail of the plan have been a closely guarded secret, but key elements are lowering rates for individuals and businesses and scrubbing the code of all but the most popular exemptions.

The president has stood firm on the promise to retain deductions for home mortgage interest and charitable donations. He also wants to get rid of deductions and loopholes that benefit big corporations and the super wealthy, accordion to officials.

To sell his vision, Mr. Trump is making the pitch at the Springfield factory of Loren Cook Co., which makes ventilation equipment.

The White House said the location of a manufacturing plant in Missouri on the famed former Route 66, also known as the “Main Street of America,” was emblematic of Mr. Trump’s focus on main street and small businesses.

The event is invitation only, and the audience will consist mostly of company management and workers, despite officials saying Mr. Trump was giving the speech to bring everyday Americans into the tax reform conversation.

White House officials said that the president wanted to strike a serious tone and highlight a manufacturing business, rather than hold a large campaign-style rally.

The company’s owners are also Republican donors.

The Cook company invested nearly $250,000 supporting statewide Republican candidates in the 2016 election, the Springfield News-Leader reported.

Loren Cook II and Gerald “Chip” Cook Jr. contributed to Mr. Trump’s presidential campaign. Loren Cook also contributed to the Black Conservatives Fund, according to the newspaper.

The setting is also in the home state of Sen. Claire McCaskill, one of the chamber’s most vulnerable Democrats in next year’s midterm elections. She will be under pressure to break with her party and back Mr. Trump’s plan, if he can sell it to voters in Missouri and across the country.

“There is no doubt that the president will make a bipartisan appeal on tax reform,” the White House aide said. “This is a priority for many for many years.”