US President Donald Trump is "very well" as he spends the weekend in a hospital after testing positive for coronavirus, his doctor says. Dr Sean Conley said the president was not on extra oxygen for now and had been fever-free for 24 hours. But conflicting reports have emerged suggesting concern over Mr Trump's health, the time he was diagnosed or whether he was ever given oxygen. In exactly one month, Mr Trump faces Joe Biden in the presidential election. The positive diagnosis, made public by the president in a tweet on Friday, has upended his campaign and also cast doubt on his attempt to get a new Supreme Court judge confirmed before polling day. The president is expected to remain at the Walter Reed National Military Medical Center close to Washington DC for several days. Dr Conley said he was "cautiously optimistic" but that he could not give a timetable for his discharge. But the doctors' assessment was contradicted by a person familiar with the president's condition who said some of his vital signs over the last 24 hours were "very concerning" and that the next 48 hours would be critical. The source said "we're still not on a clear path to a full recovery". The president, being 74, a man and someone categorised as obese, is in a higher-risk category for Covid-19. He has so far been treated with an experimental drug cocktail injection and the antiviral medication remdesivir. Writing on Twitter later, the president said: "Doctors, nurses and all at the great Walter Reed Medical Center, and others from likewise incredible institutions who have joined them, are amazing... With their help, I am feeling well!