WASHINGTONNews that United States President Donald Trump and First Lady Melania Trump have tested positive for Covid-19 has brought new meaning to the phrase "uncharted waters".
Politicians, pundits and constitutional lawyers are scrambling to find an answer to the question: What happens if a presidential candidate is incapacitated or dies before the election?
The question is not entirely new; the coronavirus is particularly lethal for the elderly and even more so for those with underlying health issues.
There have been concerns for both Mr Trump, 74, and his presidential rival Mr Joe Biden, 77, due to their advanced age.
Less than 48 hours before his diagnosis, the President shared a stage with Mr Biden at the first presidential debate in Cleveland, Ohiothough they did not shake hands.
Ms Hope Hicks, the President's close aide who travelled with him to Cleveland, tested positive for the coronavirus earlier on Thursday (Oct 1), setting off a scramble to test everyone else who was on that trip or on recent trips with her or the President.
Hours afterwards, the President tweeted news of his and Mrs Trump's positive tests.
Mr Trump is supposedly in very good health and neither smokes nor drinks alcohol. But no two cases of Covid-19 are alike.
Dr Richard H. Pildes, professor of Constitutional Law at New York University, was asked the question by the Washington Post in August. His answer: The ball would be in the hands of the candidate's political party.
The Democratic National Committee apparently has a clear rule for such a situation. It would choose the new nominee in consultation with the party leadership, including Democratic state governors.
But that doesn't mean a certain outcome, as it's subject to a vote. For example, if Mr Biden were to die, it's not certain whether the substitute would be his running mate Senator Kamala Harris or his primary runner-up Senator Bernie Sanders.
VP Mike Pence, who would become president in the event of Mr Trump's death, would be a top choice for the Republican Partybut not the certain pick.
The Republican National Committee (RNC) has similar rules. It's 168 membersthree from each state plus three from six territories. A vote will have to be held. The parties would then have to replace the name of their deceased candidate with that of the new candidate on each state's ballot.
"Depending on when this happens, that might not be simple," Dr Pildes said.
"Different states have different deadlines for when the parties must certify their candidates for the ballot."
Also, if states do not have laws that permit changing the candidate's name, any change may be challenged in courtalthough courts would be unlikely to refuse the new nomination if the party process has been followed.
But the wrangling could delay the process.
Separately Prof Rick Hasen, professor of Law and Political Science at the University of California at Irvine, writes: "The problem here is that ballots are already out and millions of people have already voted. At this point, it seems impossible for candidates to come up with a new name to replace a name on the ballot without starting the whole election process over, which is not possible in the 30-plus days before election day. Congress could pass a Bill delaying the election but I find it hard to believe it would do so."
One thing is nearly certain: With the President and the First Lady in quarantine, the second presidential debate due for Oct 15 will be cancelled.
Foreign policy decisions that have been largely the turf of the White House during the Trump administration may also be placed on hold.
And if the President does die - regardless of the process for a substitute candidatethere is a risk of real turmoil in a deeply divided country with an economy and a people staggering under a colossal coronavirus death toll of over 200,000.