WASHINGTON — President Trump will send a budget to Congress on Thursday that sharply reorders the nation’s priorities by spending billions of dollars on defending the Southern border and bolstering the Pentagon while severely cutting funds for foreign aid, poverty programs and the environment.
The budget would fulfill Mr. Trump’s campaign promise to shock Washington by slashing the government work force — but it is virtually ensured to be discarded by Hill Republicans who see many of Mr. Trump’s cuts as too rushed, indiscriminate and reckless.
“You can’t drain the swamp and leave all of the people in it,” Mick Mulvaney, the White House’s budget director, said during a briefing on Wednesday.
The budget would cut the Environmental Protection Agency by 31 percent, the State Department by 28 percent and Health and Human Services by 17.9 percent. Funding to several smaller government agencies that have long been targets of conservatives — like the Legal Services Corporation, the Corporation for Public Broadcasting, the National Endowment for the Humanities and the National Endowment for the Arts — would be axed entirely.
The chances of Mr. Trump’s first budget passing Congress in its current form are slim. Many of the proposals would be nonstarters for Democrats, and some would be problematic for Republicans. The proposed $54 billion increase in military spending — a 10 percent increase — would also require a repeal of spending caps imposed by the 2011 Budget Control Act; Democrats oppose such a move without equal spending increases for domestic programs.
The most significant cuts would be at the E.P.A., which the Trump administration has accused of overreach. The president wants to trim $2.6 billion from the agency’s budget, in part by cutting about 3,200 positions, about a fifth of the department’s work force.
If enacted, the proposal would cut the agency’s budget to its lowest level in 40 years, adjusted for inflation. That would mean eliminating funding for climate change research, closing state environmental programs and ending regional projects like the Great Lakes Restoration Initiative, which has bipartisan support.
Mr. Trump would also cut funding to the United Nations for its climate change efforts, and curb contributions to its peacekeeping efforts. Contributions to the World Bank would be cut by $650 million, and economic and development assistance would be “refocused” to countries of greatest strategic interest to the United States.
The brunt of the cuts at the Department of Health and Human Services would be at the National Institutes of Health, the country’s medical research hub. The $403 million currently used for training nurses and other medical professionals would also be eliminated.
Mr. Trump’s team also proposed a wide array of cuts to public education, Amtrak and the Department of Housing and Urban Development, including eliminating the $3 billion Community Development Block Grant program, which funds popular programs like Meals on Wheels, housing assistance and other community assistance efforts.
Much of the money saved by these cuts would go to national security programs.
Besides the military, the Department of Homeland Security would also receive an infusion of cash. An additional $2.8 billion would go largely to pay for a wall along the border with Mexico and the hiring of 500 Border Patrol Agents and 1,000 Immigration and Customs Enforcement officers next year. The budget also calls for the hiring of 20 lawyers in the Justice Department who would work to obtain land along the border for the wall.
The White House is expected to make a supplemental request of $1.5 billion on Thursday to get work started on the wall this year.
Government funding for the current fiscal year will run out on April 28, and the 2018 budget needs to be in place by October. Democrats in Congress warned this week that there could be a government shutdown if Republicans insisted on including funding for the wall in their request.
The $1.1 trillion plan is a “skinny budget,” a pared-down first draft of the line-by-line appropriations request submitted by first-term administrations during their first few months. A broader budget will be released in the spring that will include Mr. Trump’s tax proposals as well as the bulk of government spending — Social Security, Medicare, Medicaid and other entitlement programs.
Mr. Trump’s version is even skinnier than usual, a result of Mr. Mulvaney’s drawn-out confirmation process in the Senate.
As reports of Mr. Trump’s cuts trickled out over the last month, some Republicans made their concerns known. Senator Lindsey Graham of South Carolina declared the proposed cuts to the State Department “dead on arrival,” and Senator Marco Rubio of Florida said that foreign aid was a small investment that played an important national security role.
Mr. Trump’s proposed cuts to the E.P.A. are a magnitude greater even than those envisioned by congressional Republicans, many of whom forcefully oppose the agency’s regulatory agenda. Last year, the House spending subcommittee that controls the agency’s budget proposed funding the agency at $8 billion, cutting just $291 million from President Barack Obama’s request.
The E.P.A. administrator, Scott Pruitt, who as Oklahoma’s attorney general spoke out against some of the agency’s core missions, went to the White House on Wednesday to request a smaller cut after the budget office first presented its preferred spending level. He pressed for about $7 billion, according a person familiar with the talks. Instead, the White House slashed his budget even further, to about $5.7 billion.
At the State Department, news of the proposed cuts — rumored for weeks — were met with a mixture of disbelief and defiance. Much of the senior staff on the building’s seventh floor was recently reassigned, and nearly all of the department’s top political posts remain unfilled.
With so few senior leaders, a top-to-bottom departmental overhaul would be difficult.
Secretary of State Rex W. Tillerson is expected to be given wide latitude in how to apportion any cuts. Having spent his career at Exxon Mobil, Mr. Tillerson barely knows the department, and he has so far been unable to choose a deputy steeped in the ways of Foggy Bottom.
Under a 28 percent cut, the department’s $54 billion budget would go down to $39 billion, a number the department has not seen in inflation-adjusted terms since the Iraq and Afghanistan wars added enormous costs in staffing and security.
Many veteran diplomats said that injecting money into the Defense Department while slashing the State Department made little sense, since the functions of the two go hand in hand.
“We learned in both Iraq and Afghanistan that our military needs an effective civilian partner if victories on the battlefields are going to be converted into a sustainable peace,” said Stephen J. Hadley, Mr. Bush’s national security adviser. “And only a sustainable peace ensures that post-conflict states do not return again to becoming safe havens for terrorists.”
Steve Bell, a budget expert at the Bipartisan Policy Center, said Mr. Trump’s proposed cuts were the most severe in more than a half century. “When we passed the Reagan budget, we did not have cuts in the domestic programs anywhere near this size,” said Mr. Bell, who was staff director of the Senate Budget Committee from 1981 to 1986.
Mr. Mulvaney acknowledged that lawmakers of both parties were likely to resist changes that would affect pet projects in their states. However, he said that Mr. Trump’s budget was a sign that the president is a man of his word.
“We went to what the president said during the campaign,” Mr. Mulvaney said, “and we turned those policies into numbers.”