Washington (CNN) President Donald Trump's first budget proposal will look to increase defense and security spending by $54 billion and cut roughly the same amount from non-defense programs, the White House said Monday.

The budget blueprint, which was sent to government agencies Monday, would increase defense spending to $603 billion and decrease non-defense discretionary spending to $462 billion, Office of Management and Budget Director Mick Mulvaney said.

Two sources told CNN Monday that the cuts are expected to slash as much as a quarter of the Environmental Protection Agency's budget, a cut that one former EPA official said would be "devastating" and a current employee at the agency said would weaken the agency to the point where it can only do its most basic functions.

"This budget will be a public safety and national security budget," Trump said at a bipartisan gathering of US governors at the White House Monday, vowing substantial increases in defense, law enforcement and infrastructure spending.

The majority of "lower priority programs and most federal agencies" will see a reduction in their budget as a result of the proposal, according to an official at the Office of Management and Budget speaking with reporters on background.

The official said those cuts will come through "unauthorized programs" and places "where there is duplication, where consolidation needs to occur."

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Monday's announcement is only a budget blueprint and federal agencies will begin working with the White House to determine how to comply with their new budget. The proposals from the White House will also go to the agencies with suggestions on what to cut.

Mulvaney said Monday that the White House intends to have a budget to Congress by March 16 and have a final budget finished by "the first part of May."

A Trump administration official told CNN that all $54 billion will be cut in fiscal year 2018. Multiple officials have also made clear over the last 48 hours that the EPA and foreign aid will be cut significantly under the new plan.

The budget, one OMB official said, expects "the rest of the world to step up in some of the programs this country has been so generous in funding" over the years.

Foreign aid makes up roughly 1% of the federal budget and includes a host of programs meant to help implement national security policy. While foreign aid has long been a target for conservatives, cuts to these programs are unlikely to get the Trump administration close to the $54 billion in proposed overall cuts.

The budget blueprint, which will outline in the clearest terms to date what Trump's policy priorities will be as president, fits with Trump's pledges to increase defense spending and cut government waste as a candidate.

"Yes, it is a fairly small part of the discretionary budget, but it is still consistent with what the President said," Mulvaney said of the foreign aid cuts. "We are taking his words and turning them into polices and dollars."

Mulvaney said Trump's proposed 2018 budget will include funds for the US-Mexico border wall, an issue that animated the President's 2016 campaign.

Trump, in addition to the 2018 increase, will also seek a $30 billion in supplemental defense money for the fiscal year 2017, a senior administration official told CNN. Mulvaney said some funding for the border wall will be included that measure.

Sen. John McCain, an Arizona Republican, criticized the defense numbers as not robust enough. McCain was the lone member of his party to vote against Mulvaney and indicated he would do so during Mulvaney's consideration because he did not believe Mulvaney would offer the level of commitment to defense spending that he wanted.

"President Trump intends to submit a defense budget that is a mere 3% above President Obama's defense budget, which has left our military underfunded, undersized and unready to confront threats to our national security," McCain said in a statement on Monday.

'No more wasted money'

Congress is not mandated to follow Trump's budget plan and in the coming weeks, Republicans on Capitol Hill are expected to call administration officials to Congress to explain their proposal.

Trump said throughout the 2016 campaign that he would focus on spending cuts and tax reform, rhetoric that helped woo Republicans who questioned his commitment to other conservative principles.

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"I want the American people to know that our budget will reflect their priorities," Trump said in a budget meeting earlier this month. "We'll be directing all of our departments and agencies to protect every last American and every last tax dollar. No more wasted money."

Trump's closest advisers have also previewed dramatic changes to the federal government budget. At the Conservative Political Action Conference on Thursday, Steve Bannon, a top Trump aide, said that new administration's aim was "deconstruction of the administrative state," a comment many federal workers saw as a pledge to weaken regulatory agencies.

Monday, Trump vowed "a budget of great rationality" that would be unveiled in "great detail" during his address to a joint session of Congress on Tuesday evening.

He wasn't specific about where he planned to cut spending, saying only he aimed for a more streamlined federal government without listing any specific agency or program that might see its budget slashed.

"We're going to do more with less," Trump said, promising a government that's "lean and accountable to the people."

"With 20 trillion dollars in debt, the government must learn to tighten its belt," Trump said.

Trump's proposed cuts have already been met with concern inside the federal government's bureaucracy. EPA employees have told CNN that many inside the agency are still in denial about the incoming cuts to their budget, despite the fact that Trump and Scott Pruitt, the newly approved EPA administrator, pledged to trim the agency.

"It is clear to me, and will be to most agency employees very soon, that Mr. Scott Pruitt has been nominated and confirmed as administrator of the US EPA in order to make significant and substantial changes to the agency," John O'Grady, the president of the union that represents EPA employees, said in response to the proposed cuts.

State Department spokesman Mark Toner said State is "working with the White House and OMB to review its budget priorities."

"The department remains committed to a US foreign policy that advances the security and prosperity of the American people," Toner added.