President Donald Trump’s blood oxygen level dropped suddenly twice in recent days, but he “has continued to improve” since then, the White House physician said Sunday, adding a new layer of confusion to the president’s fight with COVID-19 even while suggesting he could be discharged from the hospital as early as Monday.

Trump’s doctors, speaking on the steps of the military hospital where he was being treated for a third consecutive day, again refused to answer key questions about his condition, including the timing of the president’s second dip in oxygen, which they neglected to mention in multiple statements the day before, or whether lung scans showed any damage.

Pressed about the conflicting information he and the White House released the previous day, Navy Cmdr. Dr. Sean Conley acknowledged that he had tried to present a rosy description of of the president’s condition.

“I was trying to reflect the upbeat attitude of the team, that the president, that his course of illness has had. Didn’t want to give any information that might steer the course of illness in another direction,” Conley said. “And in doing so, came off like we’re trying to hide something, which wasn’t necessarily true. The fact of the matter is that he’s doing really well.”

The briefing lasted just 10 minutes.

Before walking away, Conley said the president had a “high fever” and a blood oxygen level below 94% on Friday and during “another episode” on Saturday. He was evasive when asked whether Trump’s level had dropped below 90%: “We don’t have any recordings here on that.”

The level currently stands at 98%, Trump’s medical team said.

Blood oxygen saturation is a key health marker for COVID-19 patients. A normal reading is between 95 and 100. A drop below 90 is concerning. People with the virus sometimes do not realize their oxygen levels are low.

Trump offered his own assessment of his status the night before in a video from his hospital suite, saying he was beginning to feel better and hoped to “be back soon.” And he was back on social media early Sunday morning, sharing a video of flag-waving supporters, most not wearing masks, gathered outside Walter Reed National Military Medical Center.

The changing, and at times contradictory, accounts from the Trump administration highlighted a credibility crisis for the White House at a crucial moment, with the president’s health and the nation’s leadership on the line. Moreover, the president’s health represents a national security issue of paramount importance not only to the functions of the U.S. government but also to countries around the world, friendly and otherwise.

Trump’s Democratic challenger, Joe Biden, pulled his attack ads off the air during Trump’s hospitalization, and on Sunday, he dispatched senior aides to deliver a largely friendly message.

“We are sincerely hoping that the president makes a very quick recovery, and we can see him back out on the campaign trail very soon,” Biden adviser Symone Sanders said on CNN’s “State of the Union.”

She added: “This is a glaring reminder that the virus is real.”

Biden was at home in Wilmington, Delaware, on Sunday with no plans for in-person campaigning or other public appearances. Having already tested negative, he is expected to release the results of a new coronavirus test later in the day, and the campaign has pledged to disclose those results and all other future test results for the 77-year-old candidate.

On Saturday, White House chief of staff Mark Meadows told reporters outside the hospital, “We’re still not on a clear path yet to a full recovery.” In an update Saturday night, Trump’s chief doctor expressed cautious optimism but added that the president was “not yet out of the woods.”

On Sunday, Conley’s assessment was more positive, even while he acknowledged for the first time a second sudden drop in Trump’s blood oxygen level on Saturday.

Another member of the president’s medical team, Dr. Brian Garibaldi, said Trump on Sunday “has been up and around” and “feels well.”

“Our plan for today is to have him eat and drink, to be up out of bed as much as possible, to be mobile,” Garibaldi said. “And if he continues to look and feel as well as he does today, our hope is that we can plan for a discharge as early as tomorrow to the White House where he can continue his treatment course.”

Meanwhile, Trump’s handling of the pandemic and his own health faced new scrutiny.

More than 209,000 Americans have been killed by the virus, by far the highest number of confirmed fatalities in the word. In all, nearly 7.4 million people have been infected in the United States, and few have access to the kind of around-the-clock attention and experimental treatments as Trump.

The doctors revealed that Trump was given a dose of the steroid dexamethasone after the drop in oxygen levels on Saturday.

That was in addition to the single dose he was given Friday of an experimental drug from Regeneron Pharmaceuticals Inc. that supplies antibodies to help the immune system fight the virus. Trump on Friday also began a five-day course of remdesivir, a Gilead Sciences drug currently used for moderately and severely ill patients. The drugs work in different ways — the antibodies help the immune system rid the body of virus, and remdesivir curbs the virus’ ability to multiply.

Trump is 74 years old and clinically obese, putting him at higher risk of serious complications.

First lady Melania Trump remained at the White House to recover from her own bout with the virus.

Trump’s administration has been less than transparent with the public throughout the pandemic, both about the president’s health and the virus’s spread inside the White House. The first word that a close aide to Trump had been infected came from the media, not the White House. And aides have repeatedly declined to share basic health information, including a full accounting of the president’s symptoms, what tests he’s undertaken and the results.

Several White House officials have expressed frustration with the tenor of the White House’s discussion of the president’s health.

They were particularly upset by the whiplash between Conley’s rosy assessment Saturday and Meadows’ more concerned outlook. They privately acknowledge that the administration has little credibility on COVID-19, but believe they have unnecessarily squandered what remains of it with the lack of clear, accurate updates on Trump’s condition.

Most of that frustration appears to be directed at Trump himself, with aides believing that he has restricted what Conley can say or that Conley has tried to appease the president by presenting an optimistic outlook. They also blame Meadows for not establishing clear lines of communication and for making the situation worse Saturday.

At the same time, the White House has been working to trace a flurry of new infections of close Trump aides and allies. Attention is focused in particular on the Sept. 26 White House event introducing Trump’s Supreme Court nominee.

That day, Trump gathered more than 150 people in the Rose Garden, where they mingled, hugged and shook hands — overwhelmingly without masks. There were also several indoor receptions, where Trump’s Supreme Court pick, Amy Coney Barrett, her family, senators and others spent time in the close quarters of the White House, photographs show.

Among those who attended and have now tested positive: former New Jersey Gov. Chris Christie, former White House counselor Kellyanne Conway, the president of the University of Notre Dame and at least two Republican lawmakers — Utah Sen. Mike Lee and North Carolina Sen. Thom Tillis. The president’s campaign manager, Bill Stepien, and the head of the Republican National Committee, Ronna McDaniel, have also tested positive, though they were not at the event. Another prominent Republican who has tested positive: Sen. Ron Johnson. R-Wis.