By JILL COLVIN, STEVE PEOPLES and ZEKE MILLER

Associated Press

BETHESDA, Md. (AP) — Infected and contagious, President Donald Trump briefly ventured out in a motorcade on Sunday to salute cheering supporters, a move that disregarded precautions meant to contain the deadly virus that has forced his hospitalization and killed more than 209,000 Americans.

Hours earlier, Trump's medical team reported that his blood oxygen level dropped suddenly twice in recent days and that they gave him a steroid typically only recommended for the very sick. Still, the doctors said Trump's health is improving and that he could be discharged as early as Monday.

With one month until Election Day, Trump was eager to project strength despite his illness. The still-infectious president surprised supporters who had gathered outside Walter Reed National Military Medical Center, driving by in a black SUV with the windows rolled up. Secret Service agents inside the vehicle could be seen in masks and other protective gear.

The move capped a weekend of contradictions that fueled confusion about Trump's health, which has imperiled the leadership of the U.S. government and upended the final stages of the presidential campaign. While Trump's physician offered a rosy prognosis on his condition, his briefings lacked basic information, including the findings of lung scans, or were quickly muddled by more serious assessments of the president's health by other officials.

In a short video released by the White House on Sunday, Trump insisted he understood the gravity of the moment. But his actions moments later, by leaving the hospital and sitting inside the SUV with others, suggested otherwise.

"This is insanity," Dr. James P. Phillips, an attending physician at Walter Reed who is a critic of Trump and his handling of the pandemic. "Every single person in the vehicle during that completely unnecessary presidential 'drive-by' just now has to be quarantined for 14 days. They might get sick. They may die."

"For political theater," the doctor added. "Commanded by Trump to put their lives at risk for theater."

White House spokesman Judd Deere said Trump's trip outside the hospital "was cleared by the medical team as safe to do." He added that precautions were taken, including using personal protective equipment, to protect Trump as well as White House officials and Secret Service agents.

Joe Biden's campaign, meanwhile, said the Democratic presidential nominee again tested negative for coronavirus Sunday. The results come five days after Biden spent more than 90 minutes on the debate stage with Trump. Biden, who has taken a far more cautious approach to in-person events, had two negative tests on Friday.

For his part, Trump still faces questions about his health.

His doctors sidestepped questions on Sunday about exactly when Trump's blood oxygen dropped — an episode they neglected to mention in multiple statements the day before — or whether lung scans showed any damage.

It was the second straight day of obfuscation from a White House already suffering from a credibility crisis. And it raised more doubts about whether the doctors treating the president were sharing accurate, timely information with the American public about the severity of his condition.

Pressed about conflicting information he and the White House released on Saturday, Navy Cmdr. Dr. Sean Conley acknowledged that he had tried to present a sunnier description of the president's condition.

"I was trying to reflect the upbeat attitude that the team, 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, you know, it came off that we were trying to hide something, which wasn't necessarily true. The fact of the matter is that he's doing really well."

Medical experts said Conley's revelations were hard to square with his positive assessment and talk of a discharge.

"There's a little bit of a disconnect," said Dr. Steven Shapiro, chief medical and scientific officer at the University of Pittsburgh Medical Center.

According to CDC guidelines, "In general, transport and movement of a patient with suspected or confirmed SARS-CoV-2 infection outside of their room should be limited to medically essential purposes."

Even before Trump's motorcade outing on Sunday, some Secret Service agents have expressed concern about the lackadaisical attitude toward masks and social distancing inside the White House, but there isn't much they can do, according to agents and officials who spoke to The Associated Press. This close to the election, thousands of agents are engaged on protective duty so they can be subbed out quickly should someone test positive.

The disclosures about Trump's oxygen levels and steroid treatment suggested the president is enduring more than a mild case of COVID-19.

Blood oxygen saturation is a key health marker for COVID-19 patients. A normal reading is between 95 and 100. 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 about the timing of Trump oxygen drops. ("It was over the course of the day, yeah, yesterday morning," he said) and asked whether Trump's level had dropped below 90%, into concerning territory. ("We don't have any recordings here on that.") But he revealed that Trump was given a dose of the steroid dexamethasone in response.

At the time of the briefing, Trump's blood oxygen level was 98% — within normal rage, Trump's medical team said.

Signs of pneumonia or other lung damage could be detected in scans before a patient feels short of breath, but the president's doctors declined to say what those scans have revealed.

"There's some expected findings, but nothing of any major clinical concern," Conley said. He declined to outline those "expected findings."

Asked about Conley's lack of transparency, White House aide Alyssa Farah suggested the doctors were speaking as much to the president as to the American public, "when you're treating a patient, you want to project confidence, you want to lift their spirits, and that was the intent."

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.

Trump's treatment with the steroid dexamethasone is 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.

Garibaldi, a specialist in pulmonary critical care, said the president was not showing any side effects of the drugs "that we can tell."

The National Institutes of Health COVID-19 treatment guidelines recommend against using dexamethasone in patients who do not require oxygen. It has only been proven to help in more serious cases. Among the concerns with earlier use is that steroids tamp down certain immune cells, hindering the body's own ability to fight off infection.

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

First lady Melania Trump has remained at the White House as she recovers from her own bout with the virus.

Several White House officials this weekend expressed frustration with the level of transparency and public disclosure since the president announced his diagnosis early Friday.

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

Many in the White House are also shaken and scared — nervous that they have been exposed to the virus and confronting the reality that what seemed like a bubble of safety has become a COVID-19 hot spot. It took until late Sunday for the White House to send a generic note to staffers suggesting they not come to the building if they do not feel well.

Peoples reported from New York. Miller reported from Washington. Associated Press writers Lauran Neergaard, Jonathan Lemire and Aamer Madhani in Washington, and Bill Barrow in Wilmington, Del., and Marilynn Marchione in Milwaukee contributed to this report.