Just imagine the scene: in the biting cold of a North American winter Donald J. Trump stands on the steps of the U.S. Capitol building for his inauguration on January 20, 2021.
But, flanked by his own security and his own supporters, Joe Biden is there, too.
Each man is claiming to have won. Never mind what had happened in the vote count, in the selection of electoral college voters from each state, in the decisions of the Supreme Court: neither candidate is standing down.
It is the stuff of nightmares: the end of that great experiment in self-government that America represents.
In the history of the U.S., with its many twists and turns and crises and assassinations and unrest: in all of that history, voters have managed every four years to elect a president and a vice president and for that election to be accepted (sometimes just about) by the nation.
Forty-five of the 50 states have been declared for one of the candidates with the others on a knife-edge
What, now, if two people whose supporters regard them as presidents-elect, turn up to take the oath?
It is worth saying clearly that this outcome is not yet likely.
At the moment one of the contenders, Donald Trump, who claimed victory very early, is insisting that he has been robbed of a second term by fraudulent postal voting.
His opponent, who as I write is inching towards the White House with narrow victories in Wisconsin and Michigan, is merely pointing out, correctly, that not all the votes have been counted.
In other words, Joe Biden is not messing with the fundamental tenets of American democracy.
Plenty of Democrats, however, think Donald Trump is doing exactly that with his shrill claims about mystery ‘ballot dumps’ in Democrat-run states that whittled away his lead.
US President Donald Trump speaks at the White House in Washington on November 4
The President took to Twitter to tell his supporters that he was leading in many key states last night before they ‘started to magically disappear’
So what would happen if the courts listened to him and stopped the count in the key swing state of Pennsylvania where a result is not expected until tomorrow?
Or what if the Democrats win a state, with all the TV pundits calling it for them — but there is a challenge mounted against some of the votes and the ‘result’ has to be reversed?
What if the courts side with Donald Trump and the matter goes to the very top: to the Supreme Court whose decisions are final?
This is where it gets dangerous. Probably Trump’s biggest domestic achievement has been to re-mould the Supreme Court.
When he came to power it was an evenly balanced body between conservative and more liberal judges.
Now, in just the past few days, he has destroyed that balance for a generation. He had already appointed two Justices cut from conservative cloth; in Amy Coney Barrett, his latest choice, he tipped the court into a six to three majority for conservatives.
He thinks that this court is his route to victory. Many Democrats would see a court so closely allied to Donald Trump as an illegitimate body. They may refuse to accept its ruling.
Democratic presidential nominee and former Vice President Joe Biden speaking to the crowds as the results begin to come through
Protesters march through Uptown in Minneapolis lighting off fireworks as election numbers from across the country started to come in
And this is where the scenario of two would-be presidents jostling each other on the steps of the Capitol becomes a little less far-fetched. It may be that Biden, 77, Obama’s vice president and a veteran Washington DC insider, would feel that he should ‘accept the result for the good of the nation’. But there are too many in Biden’s own party who would force him to fight on.
Hillary Clinton herself, in an interview back in August, was icily clear: ‘Joe Biden should not concede under any circumstances,’ she said. When Al Gore conceded to George W. Bush in 2000 after the Supreme Court intervened in that election count — remember the controversy of the ‘hanging chads’? — most Democrats reluctantly supported their leader. They were angry — some still are — but they accepted that they had to give way.
Would they do the same now? But on the other side, who can see Donald Trump turning down the opportunity to take this as far as he can?
If the Supreme Court refuses to hear a case or if they decide against him, will he simply slink away into history?
What Trump is good at — no, what he is brilliant at — is creating confusion, muddying waters. He is the Discombobulater-in-Chief. The threat is not that he merely stays in the White House till he is escorted out.
The real threat is of something much trickier for America to deal with. It’s the threat that he stays in the White House and creates a believable impression that the mess of the 2020 election is sufficient reason for him to stay.
What if states where the Governor is a Democrat say Biden won, but the legislature dominated by the Republicans insist it’s Trump, and they each send two sets of electoral college voters to the convention, due to meet on December 14, to confirm the result?
And what if Donald Trump says it is only right that he remains in situ until that clash is resolved?
The courts could become clogged with objections filed by both sides and might not reach a solution before that day in January when Mr Trump’s term, says the Constitution, has to end or be formally re-started.
Of course, there is a further reason why Mr Trump might be very keen to keep spinning this scenario out. He might want to exact a price for his departure, if indeed he finally loses. Donald Trump, the thinking goes, needs a guarantee that he can stay out of jail, or at least out of deep financial and legal trouble.
If he were to lose now and accept the loss, there is a long list of court cases waiting to be brought against him. Some are minor but some, such as alleged tax fraud (which he denies), are way more serious and, because they are state crimes, not capable of being pardoned by a president.
Perhaps, to save the nation, the prosecuting authorities might make an exception and come up with a deal to get him to go.
This is already a moment of peril for America because its laws are not designed for a moment like this. They are designed to facilitate the settling of disputes.
What if they will not, cannot, settle the most fundamental dispute of all: who should be in charge?
Justin Webb is a presenter on BBC Radio 4’s Today programme and former North American Editor, BBC News.