The White House is seeking major cuts in funding for the State Department and Environmental Protection Agency, a top official said Wednesday.

In the annual budget to be released Thursday morning, the Department of State will see a 28 percent drop in funding, including a reduction in foreign aid spending. The cut makes good on previous White House promises to reduce State Department spending in order to offset increases for the Department of Defense, which is getting a $54 billion boost.

The EPA will see its budget trimmed by about 25 percent, according to Office of Management and Budget Director Mick Mulvaney, while federal subsidies will be ended for the Corporation for Public Broadcasting.

Trump touted the cuts at a rally in Nashville, Tennessee, saying the budget "will shrink the bloated federal bureaucracy — and I mean bloated."

The cuts to the State Department budget have spurred critics who say it's another example of the diplomatic agency being sidelined in a Trump administration. Still, Mulvaney said he believes the "core diplomatic function" of the department remains intact.

Trump's top diplomat appeared to back the cuts to the agency he now leads, saying the State Department was "coming off a historically high level of funding."

"As time goes by there will be fewer military conflicts we're engaged in … [and] more effective aid and disaster assistance," Secretary of State Rex Tillerson told journalists during a press conference in Tokyo, Japan, where he was meeting officials on Thursday. "We are going to be undertaking a very comprehensive look at how programs are implemented."

Earlier, Mulvaney said he saw the budget as a follow through on President Donald Trump's promises from the campaign trail.

"If he said it on the campaign, it's in the budget," Mulvaney told reporters Wednesday afternoon in a preview of the spending plan's release.

In keeping with that approach, one of Trump's hallmark promises sees a tangible first step toward its realization: The budget puts $1.5 billion toward building a wall on the border with Mexico, with $2.6 billion more allocated for the project in the following fiscal year.

Related: White House to Propose $54 Billion Boost in Defense

As supporters in Nashville cheered for the president to "build that wall," Trump assured them he would follow through. "Don't even think about it: we will build the wall!" he said.

Calling the administration's first spending plan "the America First Budget," Mulvaney said it was crafted by channeling Trump.

"We wrote it using the President's own words," the OMB chief said. "We went through his speeches, went through articles that had been written about his policies, we talked to him and we wanted to know what his policies were and we turned those policies into numbers."

The prioritization of defense spending had been clear since Trump took office and the $54 billion increase has been previously disclosed. The Department of Homeland Security will also see a 6 percent increase in funding.

The budget won't be in balance, but Mulvaney said the plan was done so as not to increase the deficit, either. "If we spent a dollar, we reduced a dollar," he said.