Goffstown, New Hampshire - Joe Biden clashed with Donald Trump over health care and social benefits on Monday as the president unveiled a new budget plan during a visit to New Hampshire.

Trump, who is seeking a comeback to the White House, said in an interview on Monday that he would back cuts to social spending.

"There is a lot you can do in terms of entitlements in terms of cutting," he told CNBC.

The Republican was asked about the possibility of cuts to the three pillars of US social welfare: Medicare, Medicaid, and Social Security.

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Biden hit right back in an event in Goffstown, New Hampshire, accusing Trump of backing measures that would favor wealthy Americans.

"The bottom line is, he's still at it," the 81-year-old said. "I'm never going to allow that to happen. I won't cut Social Security, I won't cut Medicare."

Biden's comments came after he published an ambitious 2025 budget proposal that included a tax hike on billionaires and plans to strengthen social spending programs.

The budget is almost certain to be dead on arrival in the sharply divided US Congress but was designed to highlight his policy differences ahead of his likely rematch with Trump.

In New Hampshire, Biden accused Trump of wanting to cut taxes on the rich and said his own economic and social policies had sparked an "American comeback."

"I believe we're moving into a future where health care is a right, not a privilege in America," said Biden.

Less than eight months out from the November 5 election, Biden and Trump have gone into full battle mode after they both dominated their parties' Super Tuesday primaries last week.

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The Democrat is now embarking on a tour of battleground states, riding the momentum from a well-received State of the Union speech on Thursday that zeroed in on Trump.

The 77-year-old, who has been branded a threat to democracy, was impeached twice while in office and now faces four criminal indictments, including two for trying to overturn the election result four years ago.