Budget for next year – and an update for the year already begun – will pay for Trump's border wall between the U.S. and Mexico

The result could lead to massive deficits unless the economy grows enough to increase tax receipts significantly

Trump is expected to release his final budget proposal in mid-March but White House and Capitol Hill aides are spilling details

The White House's budget will boost defense spending and slash funding for longtime Republican targets like the Environmental Protection Agency

President Donald Trump's first budget will propose a whopping $54 billion increase in defense spending and impose corresponding cuts to domestic programs and foreign aid.

The increase was unveiled by the White House hours after he told the nation's governors he would re-tool the military to 'only do one thing – win'.

A tub-thumping Trump promised that the U.S. would not enter wars unless it would win them and that he would fund the military for that purpose.

Shortly after the White House went through details of his budget plan for the Pentagon, saying it would prioritize military might, including the nuclear triad.

It will also including funding to pay for the president's promised border wall between the U.S. and Mexico – including money added to the budget Barack Obama left behind for the fiscal year that began last fall.

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President Donald Trump is preparing to cut spending across the federal government in order to free up $54 billion to boost military spending

White House Budget Director Mick Mulvaney spoke at Monday's daily press briefing, boasting of a $54 billion boost for the Pentagon in President Donald Trump's first annual budget

Trump has said the U.S. military was 'decimated' under previous administrations, and pledged during the presidential campaign to build it back up

The budget plan 'prioritizes rebuilding the military including restoring our nuclear capabilities, protecting the nation and securing the border, enforcing the laws currently on the books, taking care of vets, and increasing school choice,' White House Budget Director Mick Mulvaney told reporters on Monday.

'And it does all of that without adding to the currently projected FY 2018 deficit.'

The wall's construction will be launched with 2018 budget dollars, Mulvaney added, along with 'some money in a future supplemental for 2017,' meaning the White House plans to pad the final budget President Barack Obama left behind.

Mulvaney described a 'pass back' process that involves the White House telling each cabinet agency how much it's expected to cut from the previous budget, and offering suggestions for how to reach that goal.

Agencies traditionally have a chance to argue against the expected cuts as well.

But the administration plans to send Congress the resulting budget 'blueprint' by March 16.

But that document, Mulvaney cautioned, is a so-called 'skinny budget' containing nothing about 'mandatory spending, entitlement reforms, tax policies, revenue projections or the infrastructure plan.'

The final, fleshed-out budget will come later, in May. Its centerpiece is expected to be the Pentagon's $54 billion raise, which Mulvaney called 'one of the largest increases in history.'

He said the offsetting budget cuts in other domestic programs would also be 'the largest proposed reduction since the early years of the Reagan administration.'

Treasury Secretary Steven Mnuchin has said cuts to Social Security and Medicare would not be part of the administration's first budget

Director of the Office of Management and Budget Mick Mulvaney (right) is in charge of hammering out a budget that reflects Trump's domestic and international policy goals

Trump told governors gathered at the White House on Monday that 'we must ensure that our courageous servicemen and women have the tools they can be to deter war, and when called upon to fight in our name, only do one thing – win.'

'We have to win. We have to start winning wars again,' said Trump. 'We don't fight to win. We've either got to win or don't fight it at all.'

The approximately 10 percent increase for the Pentagon would fulfill a Trump campaign promise to build up what he has called a 'decimated' military.

That money will come from slashing funding for the Environmental Protection Agency and other agencies that Republicans have long targeted.

Next month's 'topline' budget 'reduces money that we give to other nations, it reduces duplicative programs, and it eliminates programs that simply don't work,' Mulvaney said Monday.

'The president is going to protect the country, and do so in exactly the same way that every American family has had to do over the last couple years, and that's prioritize spending.'

Trump's first major fiscal marker will land in the agencies one day before his first address to a joint session of Congress.

For Trump, the primetime speech is an opportunity to refocus his young presidency on the core economic issues that were a centerpiece of his White House run.

Trump offered a toast during the annual Governors' Dinner at the White House in Washington, D.C. on Sunday night

The president previewed a boost in military spending during a speech Friday to conservative activists, pledging 'one of the greatest build-ups in American history.'

'We will be substantially upgrading all of our military, all of our military, offensive, defensive, everything, bigger and better and stronger than ever before,' he said.

In an interview with Fox News Channel's 'Sunday Morning Futures,' Treasury Secretary Steven Mnuchin said cuts to Social Security and Medicare would not be part of the administration's first budget. Trump's priority is passing legislation to reduce middle-class and corporate taxes, he said.

As a candidate, Trump promised to leave major entitlements untouched, breaking with some Republican leaders who believe the costly programs need to be reformed.

Still, Democratic leaders on Capitol Hill weren't impressed.

While neither House Minority Leader Nancy Pelosi nor Senate Minority Leader Chuck Schumer had seen the particulars of any Trump budget plan by Monday afternoon, they both fretted about domestic cuts.

Schumer said he believed 'middle class people, working families are going to be hurt.'

'They are almost certainly, by what they've said, [going to] breathe dirtier air and drink dirtier water, even after we've had Flint,' the New York Democrat told reporters at the National Press Club Monday afternoon.

Pelosi said she hoped the Trump administration would reconsider and any cuts or increases in spending 'would be shared between the domestic investments we make in our future, as well as the necessary investments we make in our security.'

She wasn't hopeful.

'This is a really bad path that we have seen so far and I don't even know if the president really understands the ramifications of the cuts that have been proposed,' Pelosi said.

Rep. Barbara Lee, a far-left California Democratic lawmaker, blasted the Trump administration's budget proposal on Monday afternoon.

'Sadly, the Trump Administration would rather fund endless wars and line the pockets of billionaires than help American families get ahead,' she said in a statement.

'Let me be clear: this budget was written for defense contractors, polluters and special interests. It will gut lifesaving safety net programs and environmental protections while offering massive handouts to the military-industrial complex.'