White House rivals Hillary Clinton and Donald Trump were still flailing for a knockout blow Monday as a presidential race that has cast a pall over US democracy neared its end.
With one day of campaigning left, both sides had packed schedules in the swing states that will decide whether the Democrat can convert her slim opinion poll lead into final victory.
Trump, a populist tycoon who co-opted the Republican Party and created a raucous, nativist grassroots movement in his own image, was still campaigning at midnight Sunday.
Branding 69-year-old Clinton the "most corrupt candidate ever to seek the office of the presidency," he urged supporters to "deliver justice at the ballot box on November 8."
Clinton, the former secretary of state running to become America's first female president, had events planned through midnight Monday to take her into polling day itself.
The Democrat spent the last eight days of campaigning under a renewed FBI inquiry into whether she had exposed US secrets by using a private email server at the State Department.
That burden was finally lifted on Sunday, when the FBI confirmed it would not seek criminal charges, but at the cost of another cycle of headlines about an issue that has hurt her.
She tried to end Sunday's round of rallies on a note of optimism about the United States, albeit couched as a warning that her supporters need to rise to counter the Trump threat.
"I really want each and every one of us to think for a moment about how we would feel on November 9, if we were not successful," she said in Manchester, New Hampshire
"When your kids and grandkids ask you what you did in 2016, when everything was on the line, I hope you'll be able to say you voted for a better, stronger, fairer America."
The world has looked on agog during the campaign, as Trump's once mocked reality television shtick became a plausible vehicle for victory in a divided and suspicious country.
World markets were rocked last month when the renewed FBI probe threated to sink Clinton's chances, and Asian exchanges opened higher after that threat was lifted.
But Trump came back fighting, and experts said the renewed scandal had already damaged the Democratic former first lady's chance of succeeding President Barack Obama.
Clinton's lead dropped from 5.7 to 2.9 percentage points in the week since the scandal returned, according to influential data journalist Nate Silver of FiveThirtyEight.com.
Trump is predicting a ballot upset on a par with Britain's shock vote this year to quit the European Union, or what on Sunday he called: "Brexit plus, plus, plus."
Clinton has booked a star-studded roster of supporters -- headlined by President Barack Obama and rock star Bruce Springsteen -- for her final events on Monday.
But Trump is also touring key swing states and was determined not to let Clinton off the hook over her email, a symbol for his supporters of the corruption of the Washington elite.
- 'Rigged system' -
"The rank and file special agents of the FBI won't let her get away with her terrible crimes," Trump told a rally in Michigan, a state won comfortably by Obama in 2012.
"Right now she's being protected by a rigged system. It's a totally rigged system. I've been saying it for a long time," he declared, as his supporters chanted "Lock her up!"
Late last month, with Clinton seemingly on a glide path to victory, a renewed FBI investigation in Clinton's email use sent shock waves through both campaigns.
Trump, the 70-year-old property tycoon and Republican flag-bearer, seized on the opening, condemning Clinton's "criminal scheme" and arguing that she is unfit to be president.
He has previously threatened to reject the result of Tuesday's vote if he loses, alleging that the race has been "rigged" by the media and the establishment elite.
Opinion polls tightened as Trump began to recover ground he lost after several women accused him of sexual assault, and the race looked headed for a photo finish.
Clinton made no direct reference to her reprieve during her Sunday campaign stops.
Instead, she hammered her opponent over his sometimes ugly rhetoric and, implicitly, the alleged covert Russian interference that have poisoned the race.
"There are powerful forces inside and outside of America that do threaten to pull us apart," she said.
"We've arrived at a moment of reckoning in this election. Our core values as Americans are being tested."
If Clinton wins, she will seek to build on Obama's cautious but progressive legacy, including his controversial health insurance reforms.
Trump has vowed to tear up the reform along with free trade agreements, to rebuild a "depleted" US military and review US alliances.
The latest polls give Clinton a narrow national lead of between three and five percentage points, but rolling averages point to a closer race, with Trump up in some swing states.
Silver has Clinton as a two-to-one favorite against Trump, but warned Sunday that her lead appears "less solid" than Obama's did before his re-election victory in 2012.