President Donald Trump reeled Monday on the eve of his first televised debate against challenger Joe Biden after a bolt-from-the-blue report showed he has been avoiding paying almost any federal income tax for years.

The scoop from The New York Times, reporting that Trump paid only $750 in federal income tax in 2016 and 2017, and none at all for 10 of the previous 15 years, was a shot to the jugular of the self-described billionaire.

Throughout his unlikely rise to power, Trump has portrayed himself as a hard-nosed businessman on a mission to drain the Washington swamp and represent what he calls "the forgotten man and woman."

Trump calls the Times' story -- which the newspaper says is based on his long secret tax returns -- false.

"The Fake News Media, just like Election time 2016, is bringing up my Taxes & all sorts of other nonsense with illegally obtained information," he tweeted Monday.

But with several new polls on Sunday once again suggesting Biden has the upper hand, the Republican goes into the debate in Cleveland on Tuesday ever more on the defensive.

A Washington Post/ABC News poll put Biden 10 points ahead of Trump nationally, at 53 to 43 percent support among registered voters, while an NBC News-Marist poll gave the Democrat a similar lead, of 54 to 44, in key swing state Wisconsin -- which Trump had carried in 2016.

Trump's Democratic challenger is homing in on the president's handling of the coronavirus pandemic and his controversial rush to fill the Supreme Court seat left vacant by the late liberal justice Ruth Bader Ginsburg.

But the tax report threatens the core of Trump's political identity -- that vaunted ability to connect with blue collar voters.

Biden, who frequently touts his early boyhood years in the hardscrabble Pennsylvania town of Scranton, has been trying to reframe the populist leader as a spoiled playboy from Manhattan.

Though its impact on voters was still far from clear, the Times' report -- which purports to reveal information that prosecutors and congressional investigators have been trying fruitlessly to obtain for years -- hands Biden piles of new ammunition.

And the Democrat's campaign immediately opened fire.

In a quickly crafted new ad, haunting piano music accompanies a montage of faces representing Americans in relatively low wage but admired jobs, listing the income tax they typically pay: $7,239 for teachers, $5,283 for firefighters, $10,216 for nurses.

Switching to footage of the president, the text then reads: "Federal income taxes paid: Donald Trump $750."

Billionaire or bust? 

The Times story raises new doubts about whether Trump is really the man with the Midas touch that he portrays or a hapless spendthrift owing a lot of people money.

Among his many unique traits, Trump makes boasting about his wealth a major part of his stump speech.

The empire of golf resorts bearing his name is even woven into the fabric of the presidency, with Trump taking his vast entourage to the properties on a regular basis.

But with Trump the first president in years to refuse to make public his tax returns, questions have long been asked.

Trump claims he can't release the returns because he is under audit. In his trademark brash style, he also once boasted that getting out of taxes "makes me smart."

On Monday, he tweeted "I paid many millions of dollars in taxes but was entitled, like everyone else, to depreciation & tax credits."

But according to the Times, Trump's tax returns show he managed large-scale tax avoidance partly because his supposedly successful businesses -- particularly the golf courses -- are such money losers.

The Times said that Trump benefited from a $72.9 million tax refund now subject to an official audit. He also reportedly took tax deductions on residences, aircraft and $70,000 in hairstyling for television appearances.

In a detail that raises the issue of potentially serious conflicts of interest for a sitting president, the Times said that loans personally guaranteed by Trump are soon due for repayment.

Drug test demand 

Even without the fresh fuel of the tax story, Tuesday's Trump-Biden debate was destined to be a brutal affair.

Trump is doubling down on attempts to smear his rival's mental state. Biden "doesn't know he's alive," is one of his new catchphrases.

As the debate nears, Trump has said they should both take a drug test.

"Joe Biden just announced that he will not agree to a Drug Test. Gee, I wonder why?" Trump tweeted Monday.

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

But his deputy campaign manager Kate Bedingfield had a blunt riposte: "Vice President Biden intends to deliver his debate answers in words. If the president thinks his best case is made in urine he can have at it."