There will be cuts to a dozen government departments, with spending slashed on campaign targets like foreign aid and the Environmental Protection Agency, as well as medical research, help for homeless veterans and community development grants.

The budget will be formally released on Thursday and is titled America First: A Budget Blueprint to Make America Great Again.

Mr Trump said: "A budget that puts America first must make the safety of our people its number one priority - because without safety, there can be no prosperity."

The $54 billion boost for the military is the largest since President Ronald Reagan's Pentagon build-up in the 1980s.

It promises immediate money for troop readiness, the fight against Islamic State militants and procurement of new ships, fighter jets and other weapons.

The 10% Pentagon boost is financed by $54 billion cuts to foreign aid and domestic agencies that had been protected by former President Barack Obama.

The budget goes after the frequent targets of the party's staunchest conservatives, eliminating the National Endowment for the Arts, legal aid for the poor and low-income heating assistance.

Law enforcement agencies like the FBI would be spared, with the border wall receiving an immediate $1.5 billion infusion in the current fiscal year, with another $2.6 billion planned for the 2018 budget year starting on October 1.

Mr Trump repeatedly claimed during the campaign that Mexico would pay for the wall when, in fact, US taxpayers will foot the bill.

Twelve of the government's 15 cabinet agencies would absorb cuts under the president's proposal. The biggest losers are Agriculture, Labour, State and the EPA. Defence, Homeland Security and Veterans Affairs are the winners.

More than 3,000 EPA workers would lose their jobs and programmes such as Mr Obama's Clean Power Plan, which would tighten regulations on emissions from power plants seen as contributing to global warming, would be eliminated.

Popular EPA grants for state and local drinking and wastewater projects would be preserved, however.

Mr Trump's proposal only covers roughly a quarter one-fourth of the approximately €4 trillion federal budget, the discretionary portion that Congress passes each year.

It does not address taxes, social security, Medicare and Medicaid, or make predictions about deficits and the economy.

Those big-picture details are due in mid-May, and are sure to show large - probably permanent - budget deficits. Mr Trump has vowed not to cut social security and Medicare and is dead set against raising taxes.