Nine days after testing positive for Covid-19, US President Donald Trump was readying to host hundreds of partisans at the White House on Saturday, in hopes of relaunching his struggling campaign less than four weeks from Election Day.

Trump has declared he is feeling "really good" -- but doubts linger over his health, with the president's doctor appearing more concerned about pleasing his star patient than communicating transparently with the public.

"Right now I'm medication-free, I'm not taking any medications as of, you know, probably eight hours ago," Trump told Fox News on Friday night, the first on-camera interview since his diagnosis and three-night hospitalization.

Trump plans to hold a rally Monday in the critical swing state of Florida -- a decision slammed as "reckless" by his election rival Joe Biden, in light of concerns the president might still be contagious. 

Undeterred, the Trump campaign announced two more rallies next week -- in battleground Pennsylvania Tuesday and in Iowa on Wednesday. 

And on Saturday dozens of Trump supporters with red "MAGA" heads were massing eagerly outside the White House to listen to an outdoor address expected to focus on law enforcement in Black communities.

"Trump is the kind of president, that if he is standing to defend a certain cause, he defends it," said one of them, a US servicemember of Mexican descent named Daniel, who said he wanted to show his support for the police.

For months, taking their cue from a president who mostly shunned, and at times mocked, the wearing of masks, White House advisors were rarely seen masked inside the West Wing.

Since Trump and his wife Melania tested positive, the mood has shifted. A source with knowledge of planning for Saturday's event said all guests will be required to wear a mask to listen to Trump give his address from a balcony.

In the crowd queuing outside, some were masked but many were not.

A similar gathering two weeks ago, to announce the nomination of conservative judge Amy Coney Barrett to the Supreme Court, has been singled out as a likely source of many of the dozens of positive cases since linked to the White House.

Anthony Fauci, the respected director of the National Institute of Allergy and Infectious Disease, has referred to it as a "superspreader event."

Many questions remain unanswered about the White House outbreak, with more than a dozen cases recorded in the president's inner circle, including his spokeswoman Kayleigh McEnany.

"When was the president's last negative Covid test?" asked Pete Buttigieg, a former contender for the Democratic presidential nomination, now tipped for a prominent role in a Biden administration should he defeat Trump on November 3.

- 213,000 Americans dead -
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, with cases again on the rise nationwide.

The seven-day average of new daily cases recorded between October 3 and 9 -- 47,184 -- was the highest since the week of August 13 to 19 with an average of 47,530 new cases, according to an AFP analysis of data from Johns Hopkins University.

"Over 213,000 Americans have died from this virus -- and the hard truth is it didn't have to happen this way," Biden tweeted on Saturday.

Barack Obama's former vice president -- who is currently riding close to 10 points ahead in national polls and has solidified his lead in key battleground states -- is continuing to campaign at his own pace.

In the Republican camp, meanwhile, there is increasingly palpable concern at the state of the race -- with some party heavyweights openly sounding the alarm.

"If on Election Day people are angry and they've given up hope and they're depressed... I think it could be a terrible election," Senator Ted Cruz warned this week.

"I think we could lose the White House and both houses of Congress, that it could be a bloodbath of Watergate proportions."

Trump insists the pollsters are all wrong -- and is counting the days until he can get back onto the campaign trail.

"The president does such a great job when he's talking directly to the American people," said his spokesman Hogan Gidley on Fox News Saturday, "without the filter of the mainstream media."