LAS VEGAS, United States (AFP) — US President Joe Biden tested positive for Covid with mild symptoms Wednesday, shortly after conceding he would consider dropping his reelection bid if doctors diagnosed him with a serious medical condition.

The 81-year-old Democrat gave reporters the thumbs up and said “I feel good” as he cut short a trip to Las Vegas and flew to his beach home in Delaware to go into isolation, which will take him off the campaign trail for days.

Biden thanked well-wishers on X, adding that “I will be isolating as I recover, and during this time I will continue to work to get the job done for the American people.”

The infection comes at a critical moment for Biden’s campaign, with the president seeking to show he is up to the job after a disastrous debate performance against rival Donald Trump sparked concerns about his health and calls from some Democrats for him to step aside.

It is also the latest development in a tumultuous few days in an already frenetic White House race that saw Trump survive an assassination attempt at a campaign rally.

Biden was forced to cancel a speech to a union representing Latino workers who will be crucial for his election bid, having attended a campaign event earlier in the day and given a radio interview.

His spokesperson Karine Jean-Pierre said Biden was vaccinated and boosted, was now taking the Covid medication Paxlovid and “continues to carry out the full duties of the office while in isolation.”

White House doctor Kevin O’Connor said Biden had complained of suffering from a runny nose, a cough and “general malaise,” but that “his symptoms remain mild.”

Biden was seen walking from his limousine to his plane at Las Vegas without a mask. “Good,” he said when asked how he felt, “I feel good.”