Video report by ITV News Washington Corespondent Robert Moore
They will walk on stage at 9pm East Coast time (2am BST) and take up their positions at their respective podiums at a university arena in Cleveland, Ohio.
For the first time in the history of presidential debates, there will be no handshake. Pandemic conditions will rule, so no physical contact is permitted between the candidates or with the Fox News moderator, Chris Wallace.
Only a few dozen people will be in the audience.
All around us here is a ring of steel and security. And that security comes in the form of both the secret service and doctors. Uniquely for a debate, the perceived threat is both human and pathogen. There are warning of protests and fears of the virus. You are not allowed to enter the debate zone without proof of a negative Covid test.
Washington Correspondent Robert Moore on the upcoming presidential debate
Once it begins, expect fireworks. Every single subject is controversial and bitterly divisive in today's America.
The handling of the pandemic. The vacancy on the Supreme Court. Race and violence in American cities. The integrity of the November election. The economy.
We know how Trump will handle these. We have watched him for years now. Three tactics.Attack. Attack. Attack.The President will go after Joe Biden's age and cognitive skills. He will accuse Biden's son of corruption in Ukraine. He will claim the former VP is a hostage of left-wing agitators and ultra-liberal forces.Trump will also argue that he is a victim of a relentless media witch hunt. He will claim his handling of the pandemic has saved millions of lives (even as he brushes over the 200,000 American death toll).The more intriguing question is how Biden will respond. Will he directly accuse Trump of corruption and of being a tax cheat and a fraud? Or will he try and avoid a bloodbath of insults that Trump is likely to win?I suspect it will be a blend of both. Biden will not avoid the open goal he has been given by the revelation of Trump's tax returns. He will express outrage that a nurse or a teacher has been paying more federal tax than a billionaire.
But Joe Biden will try and leave the stage having delivered a message that America can be healed and that the country is currently in the last-chance saloon. I will be counting how many times Biden describes this election as a "battle for the soul of America."He was asked what he must do to win the debate. Biden answered with four words: "Just tell the truth."This is being billed as the most consequential presidential debate in history.Given the state of the country, you would have to agree.