The Commission on Presidential Debates said Friday it has cancelled next week's showdown between Donald Trump and his challenger Joe Biden, after the president said he would not participate in a virtual format.

"Each (candidate) now has announced alternate plans for that date," the commission said in a statement, adding "it is now apparent there will be no debate on October 15."

The move leaves just one more debate on the schedule -- October 22 in Nashville, Tennessee -- before the November 3 election.

Debates have been a feature of every US presidential election since 1976, with three debates near the end of a campaign the standard since 2000.

The commission had announced Thursday it was converting the October 15 town hall debate to a virtual affair out of an abundance of caution because Trump had tested positive for the coronavirus.

But the president, who has been eager to return to the campaign trail and hold live events, refused to participate in the virtual format and sought unsuccessfully to return it to an in-person debate.

Biden had said earlier this week he would not debate Trump in person if he still had the virus, and his campaign called Trump's refusal to adapt to a virtual format "shameful."

"It's shameful that Donald Trump ducked the only debate in which the voters get to ask the questions -- but it's no surprise," Biden spokesman Andrew Bates said.

Trump "doesn't have the guts to answer for his record to voters at the same time as vice president Biden."

The US president meanwhile plans to hold his first live event at the White House since being diagnosed with Covid-19.

All attendees will be told to wear masks they must bring, and will have to submit to a Covid-19 screening (Saturday) morning. This will consist of a temperature check and a brief questionnaire, according to a source familiar with the preparations. 

Meanwhile, President Trump will give a public speech at the White House Saturday for the first time since testing positive for Covid-19, as he prepares a rapid return to the campaign trail just three weeks before the election.

The 74-year-old commander-in-chief has also announced a Florida rally on Monday in an attempt to relaunch his stumbling reelection campaign against surging Democratic rival Joe Biden, who called the president's behavior "reckless."

Seeking to project strength and improved health, Trump had refused to participate in next week's scheduled debate after organizers shifted it to an online format out of coronavirus concerns.

On Friday the Commission on Presidential Debates made it official, saying next Thursday's debate is scrapped, leaving an October 22 event the final Trump-Biden showdown before election day on November 3.

That prompted accusations of bias from Trump campaign communications director Tim Murtaugh, who said "there is no medical reason to stop" the October 15 debate from proceeding.

Knocked off the campaign trail by his three-night hospitalization last week, the president is in the midst of a frenetic bid to catch Biden.

On Friday, during an extended media blitz, Trump falsely claimed that Covid-19 now has a cure.

He also revealed that he'd been told he was near death at the worst of his bout with the virus, which has killed more than 213,000 Americans and severely dented his chances of winning a second term.

Saturday's speech, which a senior administration official said would be on Trump's favored theme of "law and order," will give him a chance to dispel lingering doubts about his health. 

The crowd will be on the South Lawn of the White House, while the president will speak from the balcony.

A source with knowledge of the planning said all attendees will be required to wear masks and have their temperature checked.

- 'Reckless' conduct -
On Monday, Trump will take another major step by holding a rally in a crucial battleground state.

"Will be in Sanford, Florida on Monday for a very BIG RALLY!" Trump tweeted.

The events come despite continued questions over how sick Trump was and how complete his recovery is now, with White House officials refusing to answer basic queries including when the president first contracted the virus and whether he has tested negative since.

After Trump spent months mocking Biden for staying at home during the pandemic, it is Biden who has barnstormed swing states this week.

He visited Arizona Thursday and campaigned Friday in Nevada. Trump won both states in 2016 but they are now narrowly tilting Democratic in polls.

At a drive-in style event in Las Vegas, Biden slammed the president. 

"His reckless personal conduct since his diagnosis, the destabilizing effect it's having on our government, is unconscionable," Biden said.

As he boarded his campaign plane he offered a message for those attending Trump's public events: "Good luck. I wouldn't show up unless you had a mask and were distanced."

On Friday, Trump gave a marathon interview to right-wing talk radio host Rush Limbaugh in which he said the experimental Regeneron antibody cocktail that he took as part of therapeutic treatment was "a cure."

It's "a total game changer" and "better than a vaccine," he said.

In fact, there is no cure and still no approved vaccine for the coronavirus.

- 'Medication-free' -
Later Friday he appeared in his first televised interview since he was diagnosed with the virus, telling Fox's Tucker Carlson show he is now "medication-free." 

In what the White House called an on-air "medical evaluation" the president told Fox contributor doctor Marc Siegel he has been tested again for Covid-19, saying he did not know the "numbers" but "I know I'm at either the bottom of the scale or free."

It was not clear when the interview was filmed.

Trump has repeatedly asserted that he feels fine, and he has been backed up by statements from presidential physician Sean Conley.

But in his Limbaugh interview, Trump suggested for the first time that he had been close to death, had it not been for his aggressive regimen of therapeutic drugs.

"I'm talking to you today because of it. I could have been a bad victim," he said, adding that doctors told him: "You were going into a very bad phase." 

Polls show Biden leads heavily in key demographics including women and the elderly, prompting analysts to talk increasingly of a possible landslide victory.

Trump's biggest liability -- overwhelming public dissatisfaction over his handling of the pandemic -- has returned as the headline issue of the campaign thanks to his own infection.

Adding to the pressure, Democrats who control the House of Representatives unveiled plans for a commission to investigate a president's fitness for the job -- a move clearly meant to jab at Trump.