NEW YORK — Washington finds itself in the midst of the worst constitutional crisis since the Civil War. It is slow-moving, but it is a constitutional crisis nonetheless. The crisis will come to a head at the start of 2019, when the Democrats take control of the House of Representatives and are forced to confront an illegitimate president.

In stable societies succession and transfer of power are governed by laws. Laws define the scope and reach of power, setting limits on its exercise.

But legitimacy also depends on a range of unwritten rules: on customs, traditions and a whole ranges of mores, attitudes and cultural and ethical principles which constitute the social contract. When those unwritten rules are violated it is possible to lose legitimacy without actually usurping power from the point of view of the law.

By this measure Donald Trump, a legally elected presiddnt, is an illegitimate head of state. When pundits declare on a daily basis that something Trump has said or done is unprecedented in the history of the Republic, what they are actually saying is that Trump is breaking the social contract.

Start with the fact that two of the last three U.S. presidents won the White House despite losing the popular vote. It had happened only once in history and that had been a widely recognized aberration. Now it is very likely to keep happening regularly. It is an awkward situation for a nation that takes pride in the one-person-one-vote principle and lectures the rest of the world on free and fair elections.

What is worse, the whiff of collusion with America’s bitter enemy – if not outright treason – continues to hang over Trump’s election victory, whether or not the ongoing investigation by Robert Mueller succeeds in finding the smoking gun. At last count, 14 members of Trump’s campaign and transition team had some 90 contacts with various Russians.

Trump supporters now say that collusion is not a crime while Trump is doing his damndest to impede and discredit the investigation. Yet, any traditional American politician would have been swept out of office at a mere hint of conniving with Moscow to sway an election – and of blatantly obstructing an investigation into this collusion.

Releasing tax returns is not required by law but it has long been considered the right thing to do for any presidential candidate. Trump has not done it.

Past presidents put their business interests and investments aside to avoid an appearance of a conflict of interests. Trump continues to profit from his properties, steering government business to his hotels and resorts. Foreigners know that by staying at Trump’s hotels they can influence American policy – as the Saudis have done by checking in a bunch of American veterans on a bogus lobbying trip.

American presidents have been leading champions of freedom, democracy and the rule of law around the world. Trump has fawned on dictators and has condoned the gruesome killing of a Saudi journalist – apparently because he and his son-in-law Jared Kushner do business with the Saudis.

Lying, engaging in puerile squabbles and inventing childish nicknames for political opponents and critics has not been considered presidential. Before Trump, American presidents were supposed to be serious people imbued with a sense of gravitas.

The Founding Fathers envisioned the Senate, comprised of older, mature, independent citizens, as a check on presidential power. Under Majority Leader Mitch McConnell the Senate has neglected its functions and has therefore forfeited a measure of its own legitimacy. The legitimacy crisis seems contagious: thanks to McConnell and his treatment of Barack Obama’s nominee Merrick Garland, the legitimacy of the Supreme Court has also been tainted.

Trump has always been an impostor. He claimed to be one of the world’s richest men even as his business empire was mired in bankruptcy and debt. He pretended to be a legitimate businessman while stiffing his clients, investors, lenders and contractors.. He said he was a developer while building next to nothing. He merely played all these roles in a reality TV show.

His career of a mountebank prepared him well to be an illegitimate president. He knows he is an impostor in the White House. This is why one of his first lies was about millions of illegal immigrants voting for Hillary Clinton. He even set up a commission which wasted a great deal of time and taxpayers’ money to ferret out nonexistent voter fraud.

To shore up his legitimacy, Trump started his re-election campaign in his first year in office – earlier than any legitimate president in memory. His favorite thing is to stand in front of a stadium filled with his raging supporters. The acclaim by the mob is where he seeks legitimacy. This form of government is called ochlocracy – government by the mob, as opposed to  democracy – government by the people.

As other mob leaders throughout history, Trump wants to mispresent ochlos– the mob – as demos– the people. This is why he calls the media “the enemy of the people”. In reality, the free and independent press is the enemy of the mob – as it should be.

Equally important in legitimizing Trump is his “Lock Her Up” chant still heard at his rallies. The only way he can make himself legitimate is to portray all previous American presidents as illegitimate. Hence his constant criticism of his predecessors – Democrats and Republicans alike. His acting Attorney General Matthew Whitaker – also appointed in violation of all precedent – or the next Attorney General William Barr may well do Trump’s bidding and go after Hillary Clinton. Jailing her would clearly legitimize Trump’s election victory.

This year’s midterm elections were an important test whether the American people see Trump as their president. Ahead of the elections, Trump had been telling his supporters that his name was effectively on the ballot. By this measure, Americans voted strongly against Trump. Now that the House of Representatives will be controlled by the Democrats, Trump and his Republican allies will find it harder to “normalize” Trump. But this creates a slew of other risks, both domestic and international. After all, a military adventure abroad has been the best source of instant legitimacy for shaky rulers.