US presidential hopeful Elizabeth Warren has offered details on funding for her healthcare plan, which is expected to cost the federal government $20.5 trillion over 10 years.

The Democrat Massachusetts Senator, who moved clear of her key rival former Vice PresidentJoe Biden in a poll in the early-voting state of Iowa on Friday, said “Medicare for All” would not spend “any more money overall than we spend now”, the BBC reported.

She said her plan would mandate that employers pay the government the same amount they currently contribute to private health insurance for their staff.

“The $11 trillion in household insurance and out-of-pocket expenses projected under our current system goes right back into the pockets of America’s working people,” her plan states.

“And we make up the difference with targeted spending cuts, new taxes on giant corporations and the richest 1 per cent of Americans, and by cracking down on tax evasion and fraud. Not one penny in middle-class tax increases.”

Warren added that she would raise her previously proposed wealth tax on billionaires from 3 to 6 per cent, increase corporate taxes, tax transactions such as stock trades and raise revenue through immigration reform – by turning undocumented migrants into legal, taxpaying workers

“Healthcare in America is world-class,” the Massachusetts Senator wrote in her proposal.

“Medicare for All isn’t about changing any of that. It’s about fixing what is broken – how we pay for that care.”

According to her campaign, the array of often puzzling medical bills currently faced by US patients – such as premiums, deductibles, co-pays and other out-of-pocket expenses – would be abolished, said the BBC.

Several more moderate Democratic candidates, including Biden, favour adding the option of government-run medical insurance for all Americans while allowing those who wish to keep their private medical coverage.

Warren is one of the leading contenders in the race to become the Democratic nominee in the presidential election a year from now. In the last round of debates, her rivals attacked her for lack of clarity on how she would fund Medicare for All.

Biden, with whom Ms Warren has vied for status as frontrunner, said in an interview with PBS on Friday: “She’s making it up. Nobody thinks it’s $20 trillion. It’s between $30-40 trillion. Every major independent study that’s gone out there that ‘s taken a look at this. There’s no way.”

Pete Buttigieg told Fox News on Thursday that all the candidates “have a responsibility to explain how our plans are going to be paid for”.

Later this month, the Democratic candidates who are able to meet polling and fundraising requirements will once again take the debate stage.