The great American 'experiment' with democratic institutions, so admired and followed by other nations since the 1770s, was under its worst threat since their Civil War in the 1860s.

Over the past 244 years, the 44 US presidents have been of variable quality, but they all played by the highly complex rules of US democracy. Until now.

That is why the unhinged behaviour of outgoing President Donald Trump since his defeat last November has so outraged the American people.

Like the leader of some South American junta in the 1950s, Trump seems prepared to do almost anything to hold onto power; including lying, cheating, sedition, and, sadly, the loss of life.

Until 2016, Warren Harding (1921-23) was judged the worst US president. However, his mediocre and corrupt record has been eclipsed by Trump's four years of reckless and irresponsible "leadership''.

The recent events on Capitol Hill in Washington were an appalling end to the reign of a president who is now likely to be judged as the worst in US history.

Trump claims to have been the best - such is his level of megalomania.

On January 7, the US Congress was due to vote on the 2020 US election certification, which would seal Trump's defeat. This was the final constitutional step in the ordinarily peaceful transfer of power between Republican Donald Trump and Democrat successor Joe Biden.

Instead, the outgoing President of the United States aided and abetted an insurrection.

Trump made an inflammatory address to thousands of his supporters rallying outside the White House. It bordered on sedition. The rabble then moved down Pennsylvania Avenue and invaded the Capitol building when Congress was in session.

Turning on the television that morning, I sat in disbelief, watching rioters climb the side of the building that is the citadel of American democracy.

The mob, egged on by the President, broke into both chambers before occupying various offices and trashing them. The elected representatives had to hide in other parts of the building.

According to senior Republican congresswoman Liz Cheney: "There is no question that the President formed the mob, the President addressed the mob, the President incited the mob. He lit the flame".

Washington DC police chief Charles Ramsay said the protest came "as close to a coup attempt as this country has ever seen".

But where were the security forces? It took hours for the rioters to be brought under control by the authorities, during which time five people were killed.

The world's democracies watched in shocked disbelief. Messages of extreme concern were sent by US allies, including one from Prime Minister Scott Morrison. However, I am sure the champagne corks were popping in Moscow and Beijing. These maligned dictatorial regimes would have watched with malicious satisfaction, mesmerised by their nemesis's unbelievable act of self-harm.

Despite the mob violence, the institutions of US democracy stood firm. The Congress re-convened and sat through the night until 3:45am certifying Joe Biden's electoral victory. Trump's various attempts to obstruct the democratic process since the November election has now been blocked by every authoritative institution in the US: the courts, the states, the US Congress and even his Vice-President, Mike Pence. All defied Trump. His demands were a bridge too far. In calling for the President's resignation, the conservative Wall Street Journal argued that "the President had crossed a constitutional line that he had never crossed before".

This glitch in the US system of government should pass quickly after the Biden administration takes office on January 20.

With his recent win of both senate vacancies in Georgia, the new President will control the three arms of government - both houses of Congress and the presidency. This is a sweep that the Democrats have achieved in only four of the past 40 years.

Joe Biden will now be able to fast-track the unwinding of parts of the Trump legacy because the entire government apparatus will be pulling in one direction.

The domestic problems created by the pandemic and the recession will be tackled head on.

Internationally, America will swiftly re-establish its place at the head of the free world, restore its role in international alliances, lead the fight on climate change, and more effectively resist Chinese aggression.

All of this cannot come soon enough. Trump has become the enemy of American democracy, its constitution and the will of the people. He finishes his term as president in ignominy, leaving office a diminished and isolated figure.