A country split over the credentials for Donald Trump to be its president, holds its collective breath as he spends the first days after testing positive for Covid-19 at the Walter Reed National Military Medical Center.

And as the President tweets 'Going welI, I think! Thank you to all. LOVE!!!', there are reports that his condition might not be quite as rosy as he claims.

A CNN report quoted an unnamed adviser saying there was 'reason for concern' about his condition and that the president was having 'trouble breathing'.

“This is serious,” the source said, stating that Trump was 'very tired, very fatigued' and pointing out that his condition is considerably worse than that of the First Lady.  

But the positive coronavirus test has raised the possibility that the leader of the free world could become incapacitated or potentially die in office if his condition deteriorated rapidly.

And what would happen then?

The Constitution states that the vice president is first in line to succeed the president should he or she die in office, and can step in to temporarily take on the duties of the presidency should the commander in chief become incapacitated. 

That eventuality would lead to Vice President Mike Pence, 61, who tested negative for the coronavirus on Friday, stepping up to the mark.

But there are other scenarios, not quite as rigidly enshrined, and particularly in view of the election being just a month away and wth over two million Americans already having voted. 

What happens if Donald Trump is too ill to carry out his duties?

The 25th Amendment states a president can voluntarily designate powers to their vice president if they become seriously ill or are unable to perform their duties.

In this scenario the ‘powers and duties of his office’ transfer to Mike Pence, who would become acting president. On his recovery, the President would then take back his full powers.

At this stage, no such transfer has taken place, with Donald Trump now running the country from the his presidential suite at the military hospital.

Could he be forcibly replaced?

The same Amendment also allows for a president to be removed from office if he is too ill to designate his powers or simply refuses to do so.

The constitution empowers the vice president, in conjunction with the cabinet or a group appointed by Congress, the authority to take action.

 If a majority of either group decides and informs the House and Senate that the president is ‘unable to discharge the powers and duties of his office’, then ‘the vice president shall immediately assume the powers and duties of the office as acting president’.

The arrangement would last until the president informed Congress that ‘no inability exists’ and he could perform his duties. If the group that removed his or her powers disagreed, the question would be left to Congress, with a requirement that two-thirds of the House and Senate must agree in order to strip the elected president of power.

What happens if both the president and vice-president become incapacitated?

This one is untested and therefore unclear, with the general concensus being that a carve-up of duties would be shared between the White House chief of staff, the secretary of state or other officials.

What if the President cannot run in the election?

The Republican National Committee would have to come up a new nominee, a process that would involve Chairwoman Ronna McDaniel and the 168 national members — three from each state and territory. 

The problem, given how close it is to the election, is that many people have already voted and it would be too late to add a new name to ballot papers.

Individual states would then have to come up with a plan B, given most are unlikely to already have a set of rules in place.

The plot thickens if Donald Trump were to win the election but was not able to serve as President. That Doomsday scenario would likely first go to Congress but then, inevitably, end up in the courts.