Amid the latest blast from the Republican White House nominee, his running mate Mike Pence sought to lower tensions by insisting his camp would accept defeat if that's what voters decide on November 8.
Two polls out on Sunday - and carried out in time to gauge voter reaction to the slew of sexual misconduct allegations against Trump that emerged last week - put Clinton ahead.
But they did so by vastly different numbers: an ABC News/Washington Post survey had Clinton four points ahead while an NBC News/Wall Street Journal poll put her margin at 11 points.
Trump, in a long string of tweets Sunday, said repeatedly that US media are rigging the election by hammering away at what he calls fabricated accounts that he made unwanted sexual advances against women.
Trump has denied those allegations, which burst into the race last week in a steady, damaging stream.
"Polls close, but can you believe I lost large numbers of women voters based on made up events THAT NEVER HAPPENED. Media rigging election!" Trump wrote.
Dead voters
In another tweet, he suggested - without offering any evidence - that voter fraud will be a problem on election day.
"The election is absolutely being rigged by the dishonest and distorted media pushing Crooked Hillary - but also at many polling places - SAD," he said.
Top Trump advisor Rudy Giuliani told CNN on Sunday that Democratic African-American districts are known for counting the votes of dead people.
"You want me to (say) that I think the election in Philadelphia and Chicago is going to be fair? I would have to be a moron to say that," he said, naming two cities with large black populations.
"I've found very few situations where Republicans cheat. They don't control the inner cities the way Democrats do. Maybe if Republicans controlled the inner cities, they'd do as much cheating as Democrats do," Giuliani said.
Trump has been insisting for months that the election is rigged - and has repeated the charge like a mantra since Clinton started to pull away in the polls a few weeks ago.
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"He is swinging at every phantom of his own imagination because he knows he's losing," Clinton's running mate Tim Kaine told ABC on Sunday.
Trump's assertions have been criticized as dangerous as it seems to raise the prospect of his supporters lashing out if he loses.
After the first debate Trump said he would respect the result. But he backtracked in an interview with the New York Times in late September, saying instead "We're going to see what happens."
Pence tried to put the issue to rest Sunday, saying on CBS News, "We will absolutely accept the results of the election."
He was asked about the comments of a Trump supporter who told a newspaper he planned to go to polling places and make voters "a little bit nervous."
Pence said he did not condone such behavior.
"I don't think any American should ever attempt to make any other American nervous in the exercise of their, of their franchise to vote," he said, adding that those concerned about voter fraud should volunteer at their local polling stations.
'Handed me' the election
The nation's top elected Republican, House speaker Paul Ryan, who last week declared that he would no longer "defend" the party's nominee, rebuked Trump over his comments questioning the validity of the election process.
"Our democracy relies on confidence in election results, and the speaker is fully confident the states will carry out this election with integrity," his spokeswoman AshLee Strong said in a statement.
As Trump and Clinton get ready for the last of three presidential debates in Las Vegas on Wednesday, Clinton is lying low, with the apparent strategy of letting Trump self-destruct.
But these are also delicate times for Clinton. As sexual misconduct claims against Trump dominate the campaign, is it hard for Clinton to speak out because she stayed beside her husband Bill even as he was mired in the Monica Lewinsky and other sex scandals, humiliating her on his way to being impeached.
But there is no question the race is shifting in her favor.
Another poll out Sunday was perhaps even more discouraging for Trump: the CBS News Battleground Tracker Poll found that, because of surge in support for Clinton among women, she now leads by six points in a dozen crucial swing states.
Trump even took time Sunday to target late night comedy show "Saturday Night Live," which has parodied him mercilessly in recent weeks.
He called the show "boring and unfunny" and said the actor who plays him -- Alec Baldwin -- "stinks. Media rigging election!"
His tweet came after a sketch in which the Trump and Clinton characters, debating each other, are asked what they like about each other, as happened in the actual second debate.
The Clinton character, played by Kate McKinnon, lands a zinger with an allusion to the video released October 7 in which Trump brags that he can get away with grabbing women's crotches because he is famous.
"Donald Trump and I disagree on just about everything. But I do like how generous he is. Just last Friday, he handed me this election," she says, sliding into a victory dance.
