US President Donald Trump on Sunday faced allegations that he paid little or no federal income tax for years before he came to power, as his cloudy financial past stoked controversy ahead of the first election debate.

The New York Times alleged that the billionaire president paid just $750 federal income taxes in 2016 – the year he won the White House – and 2017, and no federal income taxes at all in 10 of the previous 15 years because he reported losing more money than he made.

Trump, who immediately dismissed the accusations as “totally fake news”, is readying to come face-to-face with his Democratic opponent Joe Biden at a pivotal live debate on Tuesday.

The Republican leader has broken with presidential tradition by refusing to release his tax returns, fighting a long battle in the courts and triggering speculation about what they might contain.

“First of all, I paid a lot and I paid a lot of State income taxes too . . . It’ll all be revealed,” Trump said as he shrugged off the Times story that cited tax data extending more than 20 years.

The Times said Trump reduced his tax bill via a $72.9 million tax refund that is the subject of an Internal Revenue Service (IRS) audit. He also reportedly took tax deductions on residences, aircraft and $70,000 in hairstyling for television appearances.

Meanwhile, his golf courses report losing large amounts of money, and hundreds of millions of dollars in loans he personally guaranteed will soon be due for repayment, according to The New York Times.

Democrats jumped on the allegations, with House Speaker Nancy Pelosi saying it showed “Trump’s disdain for America’s working families”, and party colleague Chuck Schumer calling for everyone “who paid more in federal income tax” to raise their hand.

Massachusetts representative Richard Neal, the chair of the House Ways and Means Committee who has tried unsuccessfully to obtain Trump’s tax records, said the Times report makes it even more essential for his committee to get the documents.

Neal said in a statement on his Facebook page: “It appears that the President has gamed the tax code to his advantage and used legal fights to delay or avoid paying what he owes.

“Now, Donald Trump is the boss of the agency he considers an adversary. It is essential that the IRS’ presidential audit programme remain free of interference.”

Biden’s campaign team posted a tweet that simply stated how much federal income tax had been paid by teachers ($7,239), firefighters ($5,283) and nurses ($10,216) – all groups that have been hit hard by the pandemic or the West Coast wildfires, two major topics ahead of the debate.

At Tuesday’s election debate, millions of US citizens will watch as the two antagonists – who depict each other as existential threats to the country – step into the ring live on television after months of shadow-boxing.

Trump taunted Biden on Sunday with a fresh salvo on his mental acuity.

“I will be strongly demanding a Drug Test of Sleepy Joe Biden prior to, or after, the Debate on Tuesday night,” he tweeted, saying he would take one also.

“His Debate performances have been record-setting UNEVEN, to put it mildly. Only drugs could have caused this discrepancy???”

When asked by reporters about the demand, Biden laughed before declining to comment.

Both men are prone to blunders and gaffes when speaking – but the 74-year-old Trump has repeatedly depicted the 77-year-old Biden as senile.

On Saturday, Biden said he expects “personal attacks and lies” from the president, likening Trump to Nazi propaganda chief Joseph Goebbels.

The former vice-president has until recently stayed close to his Delaware home due the pandemic – while Trump has flouted his own government’s social distancing guidelines, holding jam-packed rallies with few masks in sight.

The debate also comes as both sides try to exploit Trump’s bid to install conservative Amy Coney Barrett in the late Justice Ruth Bader Ginsburg’s seat on the Supreme Court.

Trump sees his nomination of Barrett – potentially tilting the court to the right for years – as a fundamental boost to his troubled campaign.