WASHINGTON — The Trump administration proposed dramatic cuts Thursday to environmental protection, diplomacy and housing assistance as part of a budget blueprint that would ramp up defense spending and commit more than $4 billion for construction of a border wall with Mexico, setting up a battle with Democrats and potentially even fellow Republicans over government spending priorities.

In addition to a 28 percent reduction in the State Department’s budget, the Environmental Protection Agency, the Department of Housing and Urban Development and other agencies could also see double-digit percentage reductions in their funding under the administration’s plan, aides said in previewing the budget, which was released Thursday morning.

The spending plan served as a declaration of the kind of government President Donald Trump envisions and reflects the realization of many promises that he made during the campaign, seeking to add $54 billion to the Pentagon’s budget to be offset by cuts elsewhere, beginning with U.S. foreign aid. The government allocated about $28 billion for foreign aid and humanitarian assistance in the current fiscal year.

Trump sought to slash even modest federal outlays, eliminating funding for entire agencies including the National Endowments for the Arts and for the National Endowments for the Humanities, the Institute of Peace, the Chemical Safety Board and the Corporation for Public Broadcasting.

“You had an ‘America first’ candidate, you have an ‘America first’ budget,” said Mick Mulvaney, director of the Office of Management and Budget and a conservative former congressman from South Carolina. “We went looking for the most inefficient, most wasteful, most indefensible programs.”

The plan released Thursday is only the first step in a monthslong process. Exact spending levels the White House is proposing in so-called discretionary programs for the fiscal year beginning Oct. 1 will be released later Thursday. A more detailed, line-by-line plan will come in May. And along the way will be heated debates with lawmakers and other stakeholders about what programs to cut and which to preserve.

The initial blueprint reflects long-held ambitions of conservatives eager to shrink the size and scope of the federal government, with one exception for the moment: spending on entitlement programs such as Medicare, Medicaid and Social Security that are among the biggest drivers of federal spending.

The latter point is where Trump, who pledged to protect and strengthen those entrenched safety net programs, differs most dramatically with a fellow Republican who has long pushed for a new approach, House Speaker Paul D. Ryan, R-Wisconsin.

Despite Trump’s claim during the campaign that he could eliminate the national debt in eight years, this budget is not designed to reduce the deficit at all, just shift money around, so the overall level of federal debt would rise. That will be the subject of a coming fight over the debt ceiling this summer.

More immediately, the Trump administration’s plans for sweeping cuts in foreign aid may be dead on arrival with GOP lawmakers who stress the need for a more balanced approach emphasizing both military strength and a commitment to diplomacy.

“This is a hard power budget. It is not a soft power budget,” Mulvaney said. “The president very clearly wants to send a message to our allies and our potential adversaries that this is a strong power administration.”

In addition to its spending plan, the administration plans to make a supplemental funding request that will include $30 billion for defense and border protection.

The administration is seeking $1.5 billion in the upcoming fiscal year and an additional $2.6 billion the following year to begin construction of the president’s signature border wall. Mulvaney told reporters the administration will use the funds in “different pilot cases” that will help determine the safest and most cost-efficient methods for securing areas along the U.S.-Mexico border.

Barriers including fencing are already in place along about a third of the 2,000-mile border.

Though the president had promised in his campaign to help revive inner cities, the Department of Housing and Urban Development will see major spending cuts. So too will the Department of Transportation, despite Trump’s pledge to fix the nation’s crumbling infrastructure.

Mulvaney explained that the spending plan will still work to address Trump’s objectives in those areas, but that they can only be accomplished in part by eliminating programs that have failed to achieve those goals.

“One of the other things that the president said was that he was going to go after wasteful programs, duplicative programs, programs that simply don’t work. And a lot of those are in HUD,” he said. “A lot of the president’s other policies, education, for example, speak to his work that he wants to see done in the inner cities.”

Mulvaney also previewed “significant” reductions to the EPA that will target priorities of the Obama administration, including its Clean Power Plan, which was a core component of U.S. commitments as part of the landmark Paris agreement to mitigate the impacts of climate change.

Based on early reports of potential cuts in various programs, Democrats are gearing up for a major fight. A memo from the Democratic caucus on the Senate Budget Committee, led by Sen. Bernie Sanders, I-Vermont, warned that Trump’s plan “would cause even more economic pain and suffering to the elderly, the children, the sick and the most vulnerable.”

The blueprint also envisions a major retrenchment for the Department of Health and Human Services, calling for a nearly 18 percent cut next year, or $15.1 billion, for programs that are subject to annual spending bills.

Among the biggest targets is the National Institutes of Health, which would see its budget cut by $5.8 billion to $25.9 billion. The budget plan says this would “help focus resources on the highest priority research.”

Trump would also cut $4.2 billion in grants the federal government provides to communities to assist poor people, including the decades-old Low Income Home Energy Assistance Program, which helps low-income Americans with their heating bills.

And the budget would slash more than $400 million in training programs for nurses and other health professionals, which the Trump administration said are ineffective.

The mammoth health agency — the largest in government — includes the huge Medicare and Medicaid programs as well as the NIH, the Food and Drug Administration and Centers for Disease Control and Prevention.

The administration also wants to spend $1.4 billion to expand vouchers, including for private schools, and would pay for it with deep cuts to federal aid to public schools.

Voucher programs, a favorite cause of Education Secretary Betsy DeVos, provide tax funds to families that they can use to pay for tuition at private or religious schools.

The $1.4 billion in the budget would be the down payment on a program that would be “ramping up to an annual total of $20 billion,” the budget says.

Opponents of voucher programs say they would drain funds from public schools. The administration’s budget provides some support for that fear — it would cut existing education programs by about 16 percent to reduce the department’s overall budget while absorbing the new program.

The full $20 billion annual program would be roughly a third of existing federal aid to education if it were enacted.

Trump’s initial spending plan also calls for a $239 million cut to the Internal Revenue Service despite Treasury Secretary Steven Mnuchin’s public support for boosting the staff of the beleaguered tax-collection agency.

The IRS, never popular among Republicans, has been in the party’s crosshairs after the 2015 controversy over the agency’s handling of applications for tax-exempt status by conservative tea party groups.