The document will begin months of debate on government spending, with Democrats and moderate Republicans worried the budget could force tough decisions on popular programs such as aid for disabled children and hot meals for the elderly, and conservatives pushing for more cuts down the line.
New administrations typically submit to Congress what is known as a "skinny budget," a broad outline of spending proposals, in their initial months in office. Lengthy volumes of fiscal plans and projections follow a couple of months later.
But the Trump budget for the fiscal year that begins on Oct. 1, 2017, may be more truncated than usual, said three budget experts interviewed by Reuters.
The document is expected to look only at one narrow piece of the budget: “discretionary” programs that are subject to renewal every year and not so-called entitlement programs such as the Social Security retirement program and the Medicare and Medicaid health programs.
"This one appears as though it will be one of the skinniest budgets of recent memory. Possibly emaciated," said Maya MacGuineas, president of the Committee for a Responsible Federal Budget.
Social programs such as Social Security and Medicare account for the majority of overall U.S. federal government costs. Trump pledged to protect the two programs during the 2016 campaign.
"If they put out a budget as skinny as advertised, it might not really tell us a whole lot about the president's overall budget and the direction of fiscal policy," said Robert Bixby, executive director of the Concord Coalition, a nonpartisan budget reform advocacy group.
'LONG GAME'
The "skinny budget" is not expected to address other potentially expensive promises Trump made during his campaign.
Trump wants to boost infrastructure spending while cutting taxes. Although he has not given details on how or when that would happen, the pledges worry Romina Boccia, a fiscal policy expert at the conservative Heritage Foundation. “You could blow up the deficit even more,” she said.
If Trump sticks with his campaign spending promises but decides to make a bigger push to rein in the deficit, more cuts could be in store for programs such as food assistance for the poor, college Pell Grants for the poor, and some income assistance for poor senior citizens, said Sharon Parrott, senior fellow at the Center of Budget and Policy Priorities.
"That’s what’s left," Parrot said in an interview.
Trump's "skinny budget" will also make funding requests for the remaining months of the current fiscal year.
As long as increases in military spending are offset with cuts elsewhere for 2018, keeping the deficit in check, Republican Representative Steve Pearce said he was willing to wait patiently for broader fiscal belt-tightening down the road.
"We’re playing a very long game here in the debt and deficit," Pearce said in an interview.