Roughly seven hours into his congressional testimony in March, Donald Trump’s former lawyer Michael Cohen delivered a grave warning for the future of American democracy if the president does not get his way in the 2020 election.

While many during the Trump presidency have wondered if he might be impeached and removed from office during his first term, Cohen had a different concern. Like a rude house guest with the nuclear codes at his disposal, Cohen worried that the celebrity businessman-turned-president may just refuse to let go of the keys to the White House, even if he is not re-elected.

“Given my experience working for Mr Trump, I fear that if he loses the election in 2020 there will never be a peaceful transition of power,” Cohen said.

The remarks received about as much reaction from the room as a later Saturday Night Live parody of Cohen’s testimony in which he called Mr Trump racist. Which is to say, basically none.

But, it is a sentiment shared by the likes of House speaker Nancy Pelosi, who told The New York Times last week that she is preparing for just that situation.

“We have to inoculate against that, we have to be prepared for that,” Ms Pelosi said.

While Cohen’s concerns were largely disregarded, it was notable that Cohen should raise the question of what happens if the president of the United States refuses to leave office after losing an election. Could such a thing ever come to pass?

Criminals who worked for Trump Show all 5 1 /5 Criminals who worked for Trump Criminals who worked for Trump Michael Cohen Former lawyer for Donald Trump was sentenced to three years in prison on counts involving evading income tax, false disclosure of the hush money paid to Stormy Daniels and another hush money charge Getty Criminals who worked for Trump Paul Manafort Former campaign manager for Trump Manafort was found guilty in February 2018 of five counts of tax fraud, two counts of bank fraud and one count of failure to disclose a foreign bank account. The crimes occurred prior to his appointment in Trump's campaign Getty Criminals who worked for Trump George Papadopoulos Former Trump campaign adviser Papadopoulos pleaded guilty to lying to the FBI in October 2017. He had lied about making contact with a professor who claimed that the Russians had dirt on Hillary Clinton. He was sentenced to 14 days in jail Getty Criminals who worked for Trump Michael Flynn Former White House National Security adviser Michael Flynn pleaded guilty to lying to the FBI in December 2017. He had lied about conversations that he had with the Russian ambassador to the US during Trump's Presidential campaign. He was not given prison time due to his "significant assistance" to the Mueller investigation Getty Criminals who worked for Trump Rick Gates Deputy chairman of Trump's presidential campaign Gates pleaded guilty to lying to the FBI in February 2018 AFP/Getty

Experts interviewed on the possibility for this article said there is no real playbook for the scenario. Like, perhaps, the Trump administration itself, the United States would be in uncharted territory.

On previous occasions in the history of the United States, when the presidency was in any way contested, cooler heads have prevailed in the interest of the peaceful transfer of power.

Richard Nixon conceded to John F Kennedy in 1960 amid several accusations of vote rigging for the Democrat, for instance. Vice president Al Gore accepted the Supreme Court’s ruling that George Bush had won the 2000 presidential election even though there were significant questions about the integrity of the results in Florida.

Paul Quirk, a professor of political science at the University of British Columbia, says he has not given the issue a great deal of thought because it is such an outlier, but that the most likely moment of dispute would come between election day in November and January, when presidents are sworn in.

“If Trump decided that the election was illegitimate, and he was going to resist actually leaving office, he would – I don’t know whether he would try to arrest his opponent and stop them from appearing to take over the office, or whether he would just say on January 21, ‘I’m not leaving’,” Mr Quirk says.

“At some point, the question would become: whose orders do law enforcement obey? Because it would ultimately become a matter of the use of force in one direction or another.”

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The US constitution makes no mention of how a president should be removed if they lose an election and refuse to hand over power to their opponent. So, it is hard to say if anyone would have the appetite to send the FBI, or navy seals, or whatever law enforcement agency, storming into the West Wing to arrest a recently defeated Donald Trump.

Joshua Sandman, a professor of political science at the University of New Haven, says he does not think Mr Trump would ever refuse to leave office after an election because it would destroy the president’s legacy.

Still, he suggests – like other experts quoted here – intense congressional and political pressure would force Mr Trump out of office quickly.

“The first line of defence would be the congress, and his party pressuring him out, telling him he must resign or leave,” Mr Sandman says. “If he wants to stay in the White House, he would stay in the White House. But, again, hypothetically you don’t need that. The White House is symbolic. It’s not a seat of power, necessarily.”

He adds: “All of these are, it’s sort of a work of science fiction. It’s all hypothetical.”

Michael Cohen: 'I fear that if Trump loses the election in 2020 there will never be a peaceful transition of power'

Contrary to Michael Cohen’s doom-laden warning – and similar claims by the president’s former fixer, Roger Stone – the experts interviewed by The Independent say they doubted any mass uprising would actually occur if Mr Trump was to lose the 2020 election or if his presidency was terminated in congress after impeachment. As with the 2000 election, a Supreme Court decision in favour of his opponent would settle the matter.

While the president’s base of around 30 per cent of the population may be committed to him, that does not mean they would necessarily take action to keep him in office if he lost at the polls. Certainly there is no expectation that a broad swathe of the American populace would rise up to riot for a continued Trump presidency should he lose.

Ross Baker, an American political expert at Rutgers University in New Jersey, says the most challenging situation would arise if Mr Trump lost re-election by a very narrow margin.

He imagined a scenario where the popular vote was won by less than 1 per cent nationwide, and where there was a near tie in the electoral college. On 4 November 2020, America could wake up to tweets from the president calling the previous day’s results a fraud, and saying there is no way he did not win by huge margins. Meanwhile, Fox News would be welcoming pundit after pundit toeing that presidential line.

Should that happen, Mr Baker can imagine a scenario in which the House of Representatives gets to decide the electoral college based upon each state’s delegation – which may or may not line up with the popular vote.

But that does not resolve who would win or who would be the legitimate president of the United States.