BETHESDA, Md. – President Donald Trump briefly ventured out in a motorcade on Sunday to salute cheering supporters.

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 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.

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 had two negative tests on Friday.