Grand Rapids, Michigan - Donald Trump has been encouraging voters to check out a "sex tape" featuring the former beauty queen with whom he's feuding.
Hillary Clinton's campaign suggested that a better rental is the adult film in which Trump himself appears.
And then the New York Times reported that Trump might have avoided paying federal income taxes for as long as 18 years by writing off an extremely high business loss.
With the presidential campaign taking a sordid turn over the weekend, even many of Trump's supporters shook their heads, worried that their candidate's latest outburst could further hurt him among female voters already skeptical but whose support he'll badly need to win in November.
The Republican nominee's pre-dawn Twitter tirade on Friday tore into the 1996 Miss Universe, Alicia Machado, a Venezuela-born woman whose weight gain Trump has said created terrible problems for the pageant he owned at the time. Clinton had cited Trump's treatment of Machado near the end of their first debate, and Trump has spent days revisiting his complaints about Machado.
"Did Crooked Hillary help disgusting (check out sex tape and past) Alicia M become a US citizen so she could use her in the debate?" read a tweet Trump posted at 5.30am, one in a series of attacks on her.
The "sex tape" tweet apparently referred to footage from a Spanish reality show in 2005 in which Machado was a contestant and appeared on camera in bed with a male contestant. The images are grainy and do not include nudity, though Machado later acknowledged in the Hispanic media that she was having sex in the video.
Muddying the waters: an explicit 2000 Playboy video with a cameo by Trump. In a short clip posted on the website BuzzFeed, Trump pours a bottle of champagne on a Playboy-branded limo on a New York street, surrounded by a gaggle of women.
"There's been a lot of talk about sex tapes today and in a strange turn of events only one adult film has emerged today, and its star is Donald Trump," said Clinton spokesman Nick Merrill, adding he hadn't seen the film.
Meanwhile, Trump's campaign accused the media and Clinton of colluding to set him up for fresh condemnation, to which Clinton retorted: "His latest twitter meltdown is unhinged, even for him."
Machado herself took to Facebook to say Trump's tweets were part of a pattern of "demoralising women," calling them "cheap lies with bad intentions." Planned Parenthood said it showed that Trump's "misogyny knows no bounds." And Clinton said they showed anew why someone with Trump's temperament "should not be anywhere near the nuclear codes."
Shaming Machado over intimate details from her past could be particularly risky as Trump tries to win over more female voters, many of whom are turned away by such personal attacks. It also risks calling further attention to the thrice-married Trump's own history with women.
What kind of a man, Clinton asked, "stays up all night to smear a woman with lies and conspiracy theories?"
Even Trump's most vocal allies seemed at a loss for words.
"He's being Trump. I don't have any comment beyond that," said former House Speaker Newt Gingrich, a top supporter. Generally chatty and occasionally critical of Trump, Gingrich said tersely that Trump sometimes does "strange things," but that Clinton lies. "I'll let you decide which is worse for America."
But Trump's inner circle followed his lead by refusing to concede any missteps. Trump did not mention the tweets on Friday evening as he rallied supporters in Michigan. Instead, he returned to Twitter to invoke Clinton's famous ad from her 2008 campaign portraying her as the best candidate to pick up an urgent call at the White House at 3am.
"For those few people knocking me for tweeting at three o'clock in the morning, at least you know I will be there, awake, to answer the call!" Trump wrote.
On Saturday, a leaked tax document from 1995, obtained by The New York Times, revealed the tax benefits the Republican presidential nominee possibly reaped from the financial mismanagement of casinos in Atlantic City, New Jersey, his attempt to start an airline and his purchase of a large hotel in Manhattan.
According to the report, tax experts hired by the Times to analyse the three-page document said that tax rules especially advantageous to wealthy people would have allowed Trump legally to use an $916-million loss to cancel out an equivalent amount of taxable income over an 18-year period.
The New York Times reported late on Saturday that it had received the document, which shows Trump declared the $916m loss on his 1995 tax filing due to failed business ventures.
Trump's tax documents have been a major issue in the campaign because he has refused to make them public, saying they are under audit by the US tax authority. But there is no law or precedent to preclude their release, and US presidential candidates have done so for several decades.
Trump's critics have accused him of refusing the release his tax returns because he is hiding something that could be damaging to his presidential bid.
At their first debate last week Democratic nominee Hillary Clinton speculated he was not releasing them because they could reveal "he's not as rich" or "charitable as he claims." She also said that they might show "he's paid nothing in federal taxes," to which Trump interjected: "That would make me smart."
A Trump campaign statement said the Times had illegally obtained the document, but it neither challenged nor confirmed the authenticity of the document.
"Trump is a highly skilled businessman who has a fiduciary responsibility to his business, his family and his employees to pay no more tax than legally required," the statement said. It said Trump had paid hundreds of millions of dollars in other taxes over the years. These include property taxes, sales and excise taxes, real estate taxes, city taxes, state taxes, employee taxes and federal taxes.
"Trump knows the tax code far better than anyone who has ever run for president, and he is the only one that knows how to fix it," the statement said.
It added that the skills Trump has shown in building his business "are the skills we need to rebuild this country," while Clinton is a "corrupt public official who violated federal law" by using a private email server while she was secretary of state.
Clinton's campaign said the report "reveals the colossal nature of Donald Trump's past business failures." The statement, posted on Facebook, said Trump "apparently got to avoid paying taxes for nearly two decades-while tens of millions of working families paid theirs."
AP, dpa