WASHINGTON (Reuters) -- President Donald Trump said from his hospital room that the next few days will be the "real test" of his treatment for COVID-19, after a series of contradictory messages from the White House caused widespread confusion about his condition.
In a four-minute video posted on Twitter on Saturday from his hospital suite at Walter Reed National Military Medical Center, a tired-looking Trump said he was feeling "much better."
"Over the next period of a few days, I guess that's the real test, so we'll be seeing what happens over those next couple of days," Trump said into the camera, seated in front of an American flag and wearing a jacket and open-necked shirt.
Trump's illness has upended the campaign ahead of the Nov. 3 presidential election and cast a spotlight on the president's handling of the pandemic. The Republican president is trailing Democratic rival Joe Biden in opinion polls.
In an early morning tweet on Sunday, Trump said "Thank you so much!" - referring to clusters of supporters who gathered on Saturday night outside the Walter Reed hospital waving Trump 2020 flags.
Differing assessments of Trump's health from administration officials on Saturday left it unclear how ill the president had become since he tested positive for the coronavirus on Thursday night.
A White House team of doctors said on Saturday morning Trump's condition was improving and that he was already talking about returning to the White House.
Within minutes, White House chief of staff Mark Meadows gave reporters a less rosy assessment, saying, "The president's vitals over the last 24 hours were very concerning and the next 48 hours will be critical in terms of his care. We're still not on a clear path to a full recovery."
Meadows, whose initial comments were delivered on condition that he not be identified, altered his tone hours later, telling Reuters that Trump was doing "very well" and that "doctors are very pleased with his vital signs."
Meadows did not clarify the discrepancy in his comments. A Trump adviser who spoke on condition of anonymity said the president was not happy to learn of Meadows' initial remarks.
Administration officials have described the move to Walter Reed as precautionary and said Trump would stay for several days.
Another source who was briefed on Trump's condition said the president was given supplemental oxygen before he went to the hospital. The decision to hospitalize Trump came after he had experienced difficulty breathing and his oxygen level dropped, according to a source familiar with the situation.
White House doctor Sean P. Conley told reporters outside the hospital on Saturday that Trump had not had trouble breathing, and was not given oxygen at Walter Reed.
"The team and I are extremely happy with the progress the president has made," Conley said.
He declined to give a timetable for Trump's possible release from the hospital, and later had to issue a statement saying he misspoke after appearing to suggest Trump had been diagnosed as early as Wednesday.
In a statement on Saturday evening, Conley said the president was "not yet out of the woods" but his team remained cautiously optimistic.
"Today's spectacle - doctors saying one thing, White House sources saying another thing, and both later amending their statements - only reinforces the credibility problems of this administration," said Kyle Kondik, a political analyst at the University of Virginia's Center for Politics.
With Trump off the campaign trail indefinitely, his campaign announced "Operation MAGA," based on his slogan "Make America Great Again," which will see high-profile allies including Vice President Mike Pence and Trump's elder sons, Donald Jr. and Eric, take over in-person campaigning this week.
Pence, who tested negative on Friday, is scheduled to debate Democratic vice presidential nominee Kamala Harris on Wednesday.
Biden, who largely avoided direct criticism of Trump during a campaign trip to Michigan on Friday, took a more aggressive tone on Saturday while speaking to a transit workers' union, even as he wished the president well.
"I'm in a little bit of a spot here, because I don't want to be attacking the president and the first lady now," Biden said, adding he hoped Trump and his wife Melania, who also has the illness, make a full recovery.
But he quickly turned to Trump's response to the pandemic, calling it "unconscionable" and blasting Trump's comment in an interview this summer that "it is what it is" when asked about the death toll.
"I find this one of the most despicable things that I've encountered in my whole career," Biden said.
Trump has repeatedly played down the threat of the coronavirus pandemic, even as it has killed more than 208,000 Americans and hammered the U.S. economy.
British Prime Minister Boris Johnson, who himself was seriously ill with COVID-19 earlier this year, said on Sunday he was sure Trump would be fine.
"He's got the best possible care... He just needs, I mean, the most important thing to do is to follow his doctors' advice, he's got superb medical advice," Johnson told BBC television.
Biden, who tested negative on Friday, told reporters he would next be tested on Sunday. His campaign will begin releasing the results of each test, a spokesman said.
Conley said Trump had received the first two doses of a five-day course of remdesivir, an intravenous antiviral drug sold by Gilead Sciences Inc that has been shown to shorten hospital stays.
He is also taking an experimental treatment, Regeneron's REGN-COV2, as well as zinc, Vitamin D, famotidine, melatonin and aspirin, Conley has said.
A number of other prominent Republicans have also tested positive for coronavirus since Trump's announcement, including Republican senators Mike Lee, Thom Tillis and Ron Johnson, former White House senior adviser Kellyanne Conway and former New Jersey Governor Chris Christie.