Trailing Joe Biden in the polls two weeks before the election, US President Donald Trump appears to be trying to make up ground by flinging accusations without evidence that his Democratic opponent is a criminal and attacking his son, Hunter.
On Monday, Mr Trump said his opponent had been "a criminal for a long time" and
lashed out at the media "for not reporting it".
He offered no evidence to back up his allegation other than to say "read his laptop", presumably a reference to a computer once allegedly owned by Hunter that has been the subject of recent stories in the New York Post, a newspaper owned by Rupert Murdoch.
Here is what we know about Hunter:
From 2014 to 2019, while his father was vice president, Hunter, 50, a lawyer and lobbyist, served on the board of Burisma, a Ukrainian gas company.
Mr Trump accused Joe Biden of seeking the removal of Ukraine's top prosecutor in an effort to protect Burisma – and his son – from a corruption investigation while vice president.
Joe Biden acknowledged publicly that he pushed for the dismissal of the prosecutor, but the EU and International Monetary Fund also sought his removal because he not considered to be pursuing corruption aggressively enough.
Hunter told ABC News he may have displayed "poor judgment" in his past business dealings but had not engaged in any wrongdoing.
Democrats in the House of Representatives opened an impeachment inquiry in September 2019 after a whistle-blower revealed Mr Trump sought to pressure the Ukrainian president into opening an investigation of the Bidens.
The Democratic-majority House approved articles of impeachment against Mr Trump for abuse of power and obstruction of Congress but the Republican-controlled Senate acquitted him of both charges.
A report released last month by Senate Republicans into Hunter's Ukraine dealings did not find any evidence of wrongdoing by Joe Biden.
Last week the New York Post revived the allegations against Hunter with a story that claimed it obtained documents from a laptop owned by Hunter that was handed into a repair shop
but never picked up.
The newspaper claimed that emails found on the laptop showed that Hunter introduced his father to a Burisma adviser Vadym Pozharskyi in 2015 and contradict Joe Biden's claims that he never spoke to his son about his overseas business dealings.
It said the shop owner handed the laptop over to the FBI and also made a copy of the hard drive and gave it to former New York City mayor Rudy Giuliani.
Mr Giuliani, Trump's personal lawyer, has a record of dispersing disinformation about the Bidens and Ukraine.
A Biden campaign spokesman said there was no record of a meeting between the former vice president and Mr Pozharskyi.
Asked by a reporter about the Post report, Mr Biden said: "I have no response. It's another smear campaign, right up your alley."
Representative Adam Schiff, who led the Trump impeachment in the House, said it the allegations were false.
"For more than a year, Mr Trump has been desperate to create a scandal around his opponent,. He even tried to extort a foreign country into smearing Joe Biden, but failed," Mr Schiff said.
"Trump was caught and impeached over it. Now he's at it again. Different scheme. Same corrupt president."
Twitter blocked the sharing of links to the New York Post article and said there were questions about its veracity, a move which Republicans denounced as partisan censorship.
Facebook also limited distribution.
Twitter chief executive Jack Dorsey later expressed regret over how Twitter handled its communications surrounding the article, saying it was "not great".
A Republican-controlled Senate committee is seeking appearances by Mr Dorsey and Facebook chief executive Mark Zuckerberg to testify about alleged anti-conservative bias.
The Biden campaign suggested that the laptop story could be a disinformation campaign mounted by Russia, which was accused of meddling in the 2016 US election.
Director of national intelligence John Ratcliffe, who was appointed by Mr Trump, rejected that claim on Monday.
"The intelligence community doesn't believe that because there is no intelligence that supports that," Mr Ratcliffe told Fox News.
Republicans asked the FBI to reveal what it knows about the laptop.
"Are they covering up just because Hunter Biden might be engaged in things that also maybe should have been investigated and possibly prosecuted?" said Ron Johnson, a US senator and an ally of Mr Trump.
"Do we have two systems of justice, one for Democrats and one for Republicans?"
