Donald Trump vowed he and his supporters would never quit, as he charged into unexpected territory.

The candidates embarked on one of their final tours of battleground states, shifting to their closing arguments to weary voters deeply divided along racial, economic and gender lines.

With national polls showing her retaining an edge, Mrs Clinton enlisted allies and A-listers for help at stops in Pennsylvania, Ohio and New Hampshire. She planned to campaign with Cavaliers star LeBron James in Cleveland, and rally voters in Manchester with Khizr Khan, the Gold Star father whose indictment of Mr Trump delivered emotional high point for Democrats.

Mr Trump, meanwhile, planned a marathon day on the campaign trail, with stops in five states, including Minnesota, Michigan and Pennsylvania - states that have long proven unfriendly territory for Republican presidential candidates. But buoyed by a late surge of momentum, Mr Trump declared that his loyal, white working-class voters will deliver an upset on Tuesday.

Mr Trump's campaign manager Kellyanne Conway told reporters on Sunday Mr Trump planned to keep up the breakneck campaign pace through Election Day. After voting in New York, Mr Trump was expected to return to Pennsylvania, Michigan, Ohio, North Carolina and New Hampshire later in the day, Ms Conway said.

"Our secret weapon is the American people who are saying, 'enough is enough'," vice presidential candidate Mike Pence said on Fox News Sunday.

Tension ran high in the final days. Mr Trump was rushed off stage on Saturday night at rally in Reno, Nevada, after someone near the stage had shouted "Gun!," according to the Secret Service. The agency said a search revealed no weapon.

Mr Trump returned a few minutes later to resume his remarks and declared: "We will never be stopped."

The Republican candidate's son and top campaign adviser later retweeted the false rumour that the incident was an "assassination attempt", and a supporter at a subsequent rally in Denver repeated the suggestion.

Asked about the misinformation, Ms Conway did not apologise, but said Mr Trump's son was acting out of worry.

"It's pretty rattling to think of what may have happened to your father. So, I will excuse him that," Ms Conway told CNN on Sunday.

The Clinton campaign says it is focusing on securing its firewall in the West and upper Midwest.

Mrs Clinton started her day with the largely African American congregation of Mount Airy Church of God in Christ in Philadelphia. President Barack Obama planned to rally in Ann Arbor, Michigan on Monday, before joining Mrs Clinton for a rally in Philadelphia that evening.

Critical in both states is African American turnout. Black clergy were taking to the pulpits in a "souls to the poll" campaign to energise black voters, after early vote data shows some signs of diminished turnout.

Clinton campaign chairman John Podesta told NBC's Meet The Press that the campaign believes if Mrs Clinton wins Nevada and Michigan, she "is going to be the next president of the United States".

Mrs Clinton faced dark skies, intense rain and strong wind in Florida on Saturday before appearing in Pennsylvania with pop singer Katy Perry. The Democratic nominee was preparing to campaign on Sunday with basketball superstar James, having shared the stage Friday night with music diva Beyonce and hip hop mogul husband Jay Z.

"Tonight, I want to hear you roar," a smiling Mrs Clinton said before introducing Perry for a Saturday night performance in Philadelphia.

Perry, who hugged Clinton while wearing a purple cape bearing the words, "I'm with Madam President", shouted, "In three days, let's make history!"

At least 41 million Americans across 48 states have already cast ballots, according to an Associated Press analysis. That is significantly more votes four days before Election Day than voted early in the 2012.