VICE president Mike Pence has tested negative for coronavirus, and is primed to take over the Oval Office if president Donald Trump’s condition deteriorates.

He’s first in the presidential line of succession – but if the Republican were unable to carry out the duties of president, the responsibility would then fall to Nancy Pelosi, the Democrat House speaker.

Trump was last night flown to hospital, where he is expected to be for the “next few days”.

His doctor said the president was “fatigued but in goo spirits”, and is not in need of supplemental oxygen.

Late last night he tweeted from the hospital: "Going well, I think! Thank you to all. LOVE!!!"

Older men are up to twice as likely to die from Covid-19, studies have shown. And given his fondness for cheeseburgers, and a lack of exercise – other than a regular game of golf – it’s no surprise that at 17 stone, he is technically clinically obese.

A study published in August’s edition of specialist medical journal, Obesity Reviews, found that overweight people with Covid were 113% more likely than people of healthy weight to end up in hospital, 74% more likely to be admitted to an ICU, and 48% more likely to die.

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But there was little sympathy for the president who has often flouted his own government’s public health advice on close contact and mask wearing.

It’s not clear yet how long he will need to convalesce. If his symptoms are only mild he could back out on the campaign trail by mid-October – but with just 31 days left until the election, that will mean having to forgo weeks of rallies and events.

There are two more televised debates against Joe Biden to come, including one on October 15.

It’s not clear what his Democratic rival will do either. He and Trump were around 10m apart and unmasked at the debate on Tuesday night.

Trump has been trailing in the polls in recent weeks, partly down to his mishandling of the coronavirus crisis.

The US president has often played down the threat of coronavirus, cajoling schools and businesses to reopen.

In August he even threatened to divert federal funding away from schools if they chose not to reopen.

Ronald Reagan was the last president who needed to take time off to recover from injury, after he was shot in 1981. However, that was two months after he was first sworn in as American president, years before he had to stand for election. There has never been another president this unwell this close to a vote.

READ MORE: 'Will you shut up, man?': Biden and Trump exchange insults in chaotic first debate

While there is a clear line of succession in American politics, what’s less clear is when that succession needs to kick in.

The president can stand down, but if he doesn’t and his cabinet believes he is unable to perform the duties of the office, they can temporarily transfer authority to the vice president.

However, the president can easily reclaim his powers if he believes himself fit.

In the unlikely event that both Pence and Pelosi are unable to step in, the Presidency would then fall to senator Chuck Grassley, currently the president pro tempore of the United States Senate.

Next in line is the secretary of state, Mike Pompeo, and then after him is the Treasury secretary, Steven Mnuchin. The banker, worth £77m is married to Scottish actress, Louise Linton.