Updated at 4:15 p.m. ET
President Trump's budget will propose a $54 billion increase in defense spending, while slashing domestic programs by the same amount. The president told the nation's governors on Monday that his plan "puts America first," and that "we're going to do more with less, and make the government lean and accountable to people."
An official with the White House Office of Management and Budget, who spoke to reporters only if not named, said most agencies will see budget cuts, including foreign aid, which comprises less than 1 percent of federal spending.
A formal budget blueprint will be sent to Congress in March. The official said this the first step of "internal collaboration" between the White House and federal agencies.
The official said details about tax cuts and entitlement programs, including Social Security and Medicare, will come later. The administration is not expected to propose changes to entitlements.
It will be up to Congress to write the final spending plan, and it's likely there will be strong objections from Democrats to the proposed domestic cuts.
New Office of Management and Budget Director Mick Mulvaney told reporters on Monday that the president's blueprint was essentially "taking [Trump's] words and turning them into policies and dollars."
"It's a true 'America First' budget," Mulvaney said, though he stressed that this is not a full budget proposal, which won't come until May.
Already, Senate Democratic leader Chuck Schumer tweeted that Trump's budget outline would take "a meat ax to programs that benefit the middle-class."
Current defense spending is put at $590 billion, down about 25 percent from the height of the wars in Iraq and Afghanistan. Still, the U.S. spends more on the military than the next seven countries combined, according to data from 2015.
Trump called his proposed defense increase "historic," and that it will send a "message to the world in these dangerous times, of American strength, security and resolve."
"Everybody used to say America never lost a war," he said, adding, "Now we never win and don't fight to win."
He repeated his claim that the U.S. has spent $6 trillion in the Middle East, calling the situation a "hornet's nest." (PolitiFact has looked at this figure and found that it includes projected spending, beyond money that has already been spent.)
Trump said he would also increase spending for law enforcement and on infrastructure, but offered no specifics. He said he would have "big details" in his address to a joint session of Congress on Tuesday night.
Mulvaney was asked whether this budget would include funding for the president's vaunted border wall, which Trump has promised that Mexico would pay for; Mexico, however, has continued to insist it will not. Mulvaney said that he did expect some funding for that wall to be included in a future supplemental, while a 2018 budget would contain more.
It's unclear what the overall impact of Trump's plan will be on the federal budget deficit. While the proposed military buildup may be offset by domestic spending cuts, the size and nature of the yet-to-be-released tax reform proposal will determine the deficit picture.
NPR's Jessica Taylor contributed.