President Donald Trump plans to stick with his campaign pledge to slash the corporate tax rate from 35 per cent to 15 per cent, but the dramatic cut raises a problematic question for the White House: How can the president deliver the "massive" tax cut he promised without also blowing a massive hole in the budget?

A senior administration official confirmed the planned reduction to corporate rates, speaking on condition of anonymity in order discuss details of the plan the president is expected to unveil Wednesday.

Most outside economic analyses say the type of tax cuts being promoted by Trump would likely fuel even larger deficits for a federal government already projected to see its debt steadily rise. The lowered tax rates are also unlikely to generate Trump's ambitious promised growth rate of three per cent a year, roughly double the 1.6 per cent growth achieved last year. These two factors are related because the Trump administration is counting on faster economic growth to produce additional tax revenues that could then close the deficit. The concept was popularized as "trickle-down" economics during the Reagan years.

The problem is that the economy can't grow quickly enough to cover the likely hole in the deficit.

"There's no pure tax cut that pays for itself," said Alan Cole, an economist at the right-leaning Tax Foundation.

Trump has promised to release the outlines of his tax plan Wednesday and has said the plan would give Americans a tax cut bigger than "any tax cut ever." During the campaign, he backed cutting the corporate tax rate — and the personal income tax rate to 33 per cent from a top marginal rate of 39.6 per cent.

Although he did not disclose details, Treasury Secretary Steven Mnuchin said Monday the lower tax rates would generate so much economic growth that it would hold the deficit in check.

"The tax reform will pay for itself with economic growth," Mnuchin said at the White House news briefing, adding that the overhaul would ideally let someone file taxes on a "large postcard."

By running the risk of higher deficits, the Trump plan could damage the credibility of Republican lawmakers who spent years railing against the rising national debt under former President Barack Obama. Trump could also make it harder to pass lasting tax reform, since any policy that increases the debt above its baseline either requires Democratic support or — if passed by a slim majority of Republicans in the Senate — would expire in a decade. The House Republican tax blueprint tried to offset the lower rates by introducing a new tax system that applies to imports.