Donald Trump and his wife Melania have tested positive for coronavirus and will quarantine, injecting new uncertainty into a turbulent presidential election campaign just one month before the poll. “Tonight, @FLOTUS and I tested positive for COVID-19. We will begin our quarantine and recovery process immediately. We will get through this TOGETHER!” Mr Trump tweeted in the early hours of Friday.

Shortly after Mr Trump sent the tweet, the White House released a signed memo from the president’s physician confirming that both the president and his wife had tested positive for coronavirus on Thursday evening. “The president and first lady are both well at this time, and they plan to remain home at the White House during their convalescence,” Dr Sean Conley said. “I expect the president to continue carrying out his duties without disruption while recovering.” Rest assured I expect the president to continue carrying out his duties without disruption while recovering Dr Sean Conley Vice-president Mike Pence, who would take over if Mr Trump could not perform his duties, tested negative on Friday, the White House said.

Nancy Pelosi, the Democratic speaker of the House of Representatives who is second in line to take over the presidency if the president and vice-president were both incapacitated, on Friday morning said she had been tested and was waiting for the result. Ms Pelosi has not met Mr Trump recently, but she has been negotiating with Steven Mnuchin, the Treasury secretary. A Treasury spokesperson said Mr Mnuchin was tested on Friday morning and was negative. It was unclear if Mr Trump’s quarantine period would end by the next presidential debate on October 15, or how it would impact his ability to campaign in the final month of the race.

Mr Trump had started ramping up campaign rallies as he trails Joe Biden in both national polls and most swing states. Mr Trump’s campaign strategy has been to ignore or downplay Covid-19 in recent months because of criticism of his handling of the crisis, which has killed more than 207,000 Americans according to Johns Hopkins University. The US has confirmed 7.2m cases of coronavirus. In the early days of the pandemic, Mr Trump said the virus would disappear “like a miracle”. He also made claims that were ridiculed and criticised by scientists, including that people could protect themselves by injecting themselves with disinfectant.

In recent weeks, he has faced renewed criticism after Bob Woodward wrote in his new book, Rage, that Mr Trump had privately recognised the threat of the virus while telling the public there was no need for mass concern. “I wanted to always play it down,” Mr Trump told Mr Woodward in an interview. On Thursday evening, Mr Biden accused Mr Trump of doing “everything he can to distract” people from “his failed Covid-19 response”. On Friday morning, however, he sent his best wishes to his rival for the White House. “Jill and I send our thoughts to President Trump and First Lady Melania Trump for a swift recovery,” Mr Biden tweeted.

Hope Hicks, one of the president’s closest aides, tested positive for coronavirus, having been travelling with him for 2 days © Leah Millis/Reuters

Mr Trump has also questioned the effectiveness of masks — despite contrary advice from his own experts — and suggested that wearing them made some people, such as waiters, more likely to transfer the disease. At the first presidential debate, Mr Trump mocked Mr Biden for almost always wearing a mask. “Every time you see him, he’s got a mask,” he said, as both men stood on the stage without masks. “He could be speaking 200 feet away . . . and he shows up with the biggest mask I’ve ever seen.” Mr Trump was tested for the virus after Hope Hicks, a close aide who frequently travels with him to events on Air Force One, tested positive just two days after he shared the debate with Mr Biden in Cleveland, Ohio. Recommended Coronavirus pandemic Trump latest: President remained ‘well’ after positive virus test, doctor says NEW In recent weeks, Mr Trump has held several big rallies a week — a style of campaigning that helped propel him to the White House in 2016 — despite criticism from public health experts who warn that such events help spread the disease, especially when many in the audience do not wear masks.

Mr Trump insisted at the debate that his rallies had not had any impact on the spread of the virus. “We’ve had no negative effect, and we’ve had, 35 to 40,000 people at some of these rallies,” the president asserted. Herman Cain, a former Republican presidential contender who attended a Trump rally in Tulsa, Oklahoma, this summer, contracted the virus and died. US 2020 election: coronavirus and the battleground states Ms Hicks travelled with Mr Trump to the debate, which was also attended by his adult children, some of whom were pictured not wearing masks. She also accompanied him to a rally in Minnesota on Wednesday but was quarantined on the flight home after showing symptoms, US media reported.

Mr Trump’s diagnosis represents a critical moment in his presidency. While most people who contract the virus recover, it has taken the hardest roll on Americans aged 65 and over. Mr Trump is 74 and Mr Biden 77. Stock markets fell around the world after Donald Trump announced he had tested positive for coronavirus © Lee Jin-man/AP Mr Trump had been scheduled to host a rally in Florida on Friday night followed by two rallies in Wisconsin on Saturday. The White House published a revised schedule for the president on Friday morning cancelling all public events.