Question marks surround the campaign to be the next president of the USA after <a href="http://www.thenational.ae/world/the-americas/us-president-donald-trump-tests-positive-for-coronavirus-1.1086935">Donald Trump and his wife Melania tested positive for coronavirus</a>. Mr Trump said the couple would “get through this together” as they both went into quarantine. The diagnosis is one of the most serious health threats to a sitting president in decades and comes just over a month before Americans cast their vote. Here’s what it means for the November 3 election: The election is constitutionally required to take place on November 3. If Mr Trump is unable to run and withdraws from the race, the Republican national committee could pick a replacement to run on their party’s ticket. The committee could choose to nominate Mr Pence and another member of the party. All 168 members of the committee would vote on Mr Trump’s replacement. No presidential candidate has ever died or withdrawn ahead of the election. Mr Trump will not be able to campaign in person for the foreseeable future. According to Centre for Disease Control guidance, anyone in the US who tests positive for coronavirus is required to self-isolate for 10 days from the date they received the positive result. The president had been scheduled to attend a fundraiser and campaign rally in Florida on Friday night. After Mr Trump’s positive result, the White House issued a revised schedule showing several cancelled events. While Mr Trump is not currently displaying symptoms, the unpredictable nature of the disease means he could get sicker, throwing into doubt the rest of his campaign. It is thought the president will also have to miss rallies in Wisconsin and Arizona while he quarantines. Aged 74 and obese, Mr Trump is considered vulnerable. Mr Trump’s physician, Dr Sean Conley, said both the president and his wife are “well at this time” and the White House team will “maintain a vigilant watch”. The Trump campaign is feeling “optimistic” and suggested the president “would likely be fine”. It is not known how many others in the White House came into close contact with the Trumps. Questions are being asked why Mr Trump did not self-isolate after Hope Hicks, one of his closest aides, tested positive. The diagnosis marks a devastating blow for a president who has been trying desperately to convince the American public that the worst of the pandemic is behind them. In the best of cases, if he develops no symptoms, which can include fever, cough and breathing trouble, it will force him off the campaign trail just weeks before the election. In a worst case scenario, Mr Trump could fall seriously ill and may not be able to campaign at all ahead of election day on November 3. It is possible Joe Biden could get an edge on Mr Trump if he is able to travel to key swing states and win over voters. Mr Biden has consistently led Mr Trump in national polls, but surveys in battleground states suggest the vote could be much closer. It is not known if Mr Biden will decide to suspend his campaigning if his rival has to. It is not known if the next televised election debate against Joe Biden, due for October 15, will have to be cancelled or postponed. If Mr Trump completes his 10 days of isolation and is feeling better, he could theoretically still participate. One Trump campaign official suggested on BBC’s Radio 4 Today programme the debate could be held virtually. The White House said both the president and first lady were ‘well at this time’. Trump was last seen in public on Thursday afternoon, returning to the White House after a fundraising trip to New Jersey. He did not appear ill but he did not speak to reporters as he walked into his residence. Mr Trump would still be able to work from the White House if he remains feeling well. His doctor Sean Conley said: “I expect the President to continue carrying out his duties without disruption while recovering.” However, he could be forced to discharge his duties to vice-president Mike Pence if his condition deteriorates. <a href="https://www.thenational.ae/world/the-americas/donald-trump-joins-growing-list-of-leaders-infected-by-coronavirus-1.1087072">Prime Minister Boris Johnson was forced to hand over some responsibility</a> to Foreign Secretary Dominic Raab after he was admitted to intensive care suffering from coronavirus. Mr Johnson had said he was feeling fine after his positive diagnosis before falling gravely ill. The PM wished his US counterpart a speedy recovery: The positive test raises questions about what would happen if Mr Trump were to become incapacitated due to illness. The US Constitution’s 25th Amendment spells out the procedures under which a president can declare themselves “unable to discharge the powers and duties” of the presidency. If he were to make that call, Mr Trump would send a written note declaring his incapacitation. Pence would serve as acting president until Trump transmitted “a written declaration to the contrary.” The vice president and a majority of either the Cabinet or another body established by law, can also declare the president unable to discharge the powers and duties of his office, in which case Mr Pence would “immediately assume the powers and duties of the office as Acting President” until Trump could provide a written declaration to the contrary. Mr Pence’s aides had no immediate comment on whether the vice-president had been tested or in contact with Mr Trump. However, if the vice president falls seriously ill, he would be forced to hand over power to House Speaker Nancy Pelosi, who is second in the order of succession. The vice-president wished the Trumps well as the couple make their recovery: