President Donald Trump will unveil a proposed budget this week that would slash Medicaid by $800 billion over a decade and cut food stamps by 25 per cent.

Mr Trump's blueprint for the 2018 budget year comes out Tuesday. It includes reductions to benefit programmess such as Medicaid, the government insurance programme for the poorest and many disabled Americans, federal employee pensions, welfare benefits and farm subsidies.

All told, according to people familiar with the plan, Mr Trump's budget includes $1.7 trillion over 10 years in cuts from such so-called mandatory programmes.

That includes cuts to pensions for federal workers and higher contributions toward those pension benefits, as well as cuts to refundable tax credits paid to the working poor. People familiar with the plan were not authorised to discuss it by name and spoke on condition of anonymity.

Cuts include $193 billion from food stamps over the coming decade - a cut of more than 25 percent - implemented by cutting back eligibility and imposing additional work requirements, according to talking points circulated by the White House. The programme presently serves about 42 million people.

The food stamp cuts are several times larger than those attempted by House Republicans a few years back.