Donald Trump has previously said he would contest the results. If his efforts to do so are unsuccessful, the pressure on him to publicly concede defeat will mount. But does he have to?

The concession phone call from a losing candidate to the victor is a respected tradition of American politics. It is by no means obligatory, however.

In 2018, for instance, Democratic governor candidate Stacey Abrams claimed voter fraud and intimidation and never conceded to Brian Kemp, her Republican opponent.

That's never happened in a modern presidential race, however. But as in Georgia, as long as election results are legally processed and certified, the machinery of government will grind on, regardless of what Trump may do.

While Trump doesn't have to concede, or even put on a good face and attend Biden's inauguration, he does have some legal obligations. He must authorise his administration to make the logistical preparations for Biden's team to take over. That is something, according to Trump officials, the president has already done.

Donald Trump ascended to the presidency as an unconventional candidate unafraid to break long-established norms and traditions. If he so desires, he could exit the office that way, as well.

It's written in the US Constitution that the new term of office begins on 20 January at noon. So expect to see Joe Biden and Kamala Harris inaugurated on 20 January 2021, even if Trump refuses to turn up.