U.S. President Donald Trump planned to propose on Wednesday steep cuts in corporate taxes and repatriated offshore corporate profits as the administration seeks to regain momentum on economic policies.

"We'll be having a big announcement on Wednesday having to do with tax reform. The process has begun long ago, but it really formally begins on Wednesday," the president said at the Treasury Department on Friday.

A senior Treasury staffer told CNBC that Treasury Secretary Steven Mnuchin and National Economic Director Gary Cohn are set to conduct a joint news conference around 1:30 p.m. ET on Wednesday from the White House Briefing Room.

Trump has told aides to cut the income tax rate for public companies to 15 percent from 35 percent, an administration official said, according to a Reuters report.

Another official said Trump would propose a repatriation tax on offshore earnings of 10 percent, compared with the current 35 percent, the report said.

That official also said the plan would cut the top tax rate on "pass-through" businesses, which include small business partnerships, sole proprietorships and hedge funds, to 15 percent from 39.6 percent, media reports said.

The plan wasn't expected to include a "border-adjustment" tax on imports, which had proved controversial, reports said.

It is not entirely clear how much the plan will differ from the proposal Trump outlined as a candidate, or the plan that House Speaker Paul Ryan has backed. Either way, Republicans — who control both chambers of Congress — will have to hammer out fine details if they want to pass the first major tax overhaul since 1986.