President Donald Trump and Democrat Joe Biden fought Monday through the eve of an election threatened by legal chaos and fears of violence after Trump, down in the polls and with only hours to go, pushed hard to discredit the US voting process.
On Tuesday, the world will witness a country more divided and angry than at any time since the Vietnam War era of the 1970s.
All over central Washington, businesses boarded up windows in expectation of unrest and NBC News reported that a new "unscalable" fence was planned around the White House, which has been behind growing layers of fortifications since a summer of anti-racism protests.
While the Trump administration warned of left-wing extremists causing havoc, the president's supporters made their own show of force, driving in caravans of flag-bedecked pick-up trucks and blocking roads around the country.
The FBI said it was investigating an incident in Texas where Trump supporters in trucks swarmed around a Biden campaign bus while it was on a highway.
Tuesday is formally Election Day but in reality it marks only the culmination of a drawn-out election month.
With a huge expansion in mail-in voting to safeguard against the Covid-19 pandemic, more than 95 million people are estimated to have already cast ballots, highlighting the raw passion in what is turning into a referendum on the norm-shattering Republican's first term.
After four rollercoaster years, about half the country sees Trump, 74, as a historic threat whose nationalist policies, coarse manners and alleged corruption have strained the United States to breaking point.
And the other half -- evidenced in the raucous Trump rallies and chants of "we love you" -- sees in him a unique champion battling for the working class and a bulwark against rapidly advancing liberal social values.
Biden, who is polling ahead in almost every one of the swing states that tip elections, was closing up his startlingly low key campaign with socially distanced events in Ohio and Pennsylvania, the fiercest battleground of them all.
Pop superstar Lady Gaga was to join the 77-year-old, while former president Barack Obama was lending his own political star power by rallying for Biden in Florida and Georgia -- a steady Republican state targeted by the Democrats.
Trump, who mocks Biden's modestly attended events as proof that the opinion polls must be wrong, was capping his closing surge of 14 rallies in three days with visits to North Carolina, Pennsylvania, Wisconsin and Michigan.
The last rally will be in Grand Rapids -- the site where Trump delivered the final speech of his victorious 2016 campaign and where he hopes he will once more spark an upset.
Trump attacks election integrity
No election in living memory has taken place amid such tension, combining the coronavirus pandemic, violent street protests, a record shift to mail-in ballots and, increasingly, Trump's unprecedented attempts to discredit the functioning of US democracy.
The president, who for months has been falsely claiming that mail-in votes will lead to mass fraud, upped the ante in the last few days by suggesting that he will push to disqualify votes that arrive after Tuesday -- a practice which is legal in several of the key states, provided that the ballots are postmarked in time.
Together with Republican attempts to get a court to throw out more than 100,000 ballots in Texas and other aggressive legal measures, Trump's hostility to the election rules is raising fears that he will try to declare premature victory or refuse to accept defeat.
Because mail-in ballots are thought to be more likely to come from Democrats, while in-person voting on Tuesday is more likely to be Republican, the initial vote tally on election night itself may lean to Trump, while subsequent counting could in theory swing it back to Biden.
The Axios news site reported Sunday that Trump has told confidants he will declare victory right away if it looked like he was ahead.
Trump called it a "false report" but repeated his argument that "I don't think it's fair that we have to wait for a long period of time after the election."
And he has stated that he will challenge the validity of ballots in Pennsylvania immediately. "As soon as that election is over, we're going in with our lawyers," he said Sunday.