Democratic presidential candidate Hillary Clinton and her rival Republican Donald Trump have raced through major battleground states in the US to collect last-minute votes.

In the final hours of campaigning on Monday night, the candidates and their political allies travelled across the country in a last-ditch effort to sway voters.

As of Monday night, Clinton's lead over Trump had widened to 3.2 percent, according to an average of polls conducted by the website RealClearPolitics.

The figure came a day after the FBI announced that it had found no criminal wrongdoing in Clinton's use of a private email server, following a last-minute review that clouded her campaign and allowed Trump to recover ground lost in a series of recent scandals.

Campaigning in the state of Pennsylvania on Monday, Clinton promised to build a "big-hearted" America.

"Our core values are tested in this election," she said, adding that Americans should not accept "a dark and divisive vision" but "a hopeful, inclusive and a big-hearted America".

Al Jazeera's Kimberly Halkett, reporting from Philadelphia, said Clinton made the argument that she would be a president who would not divide but unite the country.

"Clinton said division would be the outcome of a Trump presidency," she said.

'Totally rigged system'

Trump delivered a speech in the crucial state of Florida, rallying against Washington, the medical-care system and Clinton, telling his supporters it was their last chance to change a broken political system.

"Hilary Clinton is being protected by a totally rigged system," he said, questioning the legitimacy of the the FBI's rapid review of a Clinton aide's emails and targeting what he called "the Washington establishment".

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"My contract with the American voter begins with a plan to end government corruption, and take back our country ... from the special interests who I know so well. When we win tomorrow, we are going to drain the swamp."

Al Jazeera's Alan Fisher, reporting from New Hampshire, said Trump's closing message stressed that Clinton was not fit to be president as she was enmeshed in various corruption scandals.

"Trump also said he would repeal and replace Obamacare, the Affordable Care Act as it is officially known in the US. And he said he would bring jobs and energy to the country," our correspondent said.

Both Clinton and Trump are by far the most unpopular candidates to run for the Oval Office in the past 30 years, according joint polling by ABC News and the Washington Post newspaper.

Since announcing his presidential campaign in June 2015, Trump, a billionaire businessman from New York, has consistently alienated minority groups, refused to release his tax returns, and remained seemingly unapologetic for leaked tapes in which he brags about sexually assaulting women.

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Clinton, who has 30 years in public service and has served as a State senator, secretary of state and first lady, is not wildly popular either.

Her campaign has been marred by the never-ending email scandal, accusations of negligence in Benghazi, Libya, and for a recent gaffe in which the candidate said half of Trump supporters belonged in a "basket of deplorabes".

If she wins Clinton will become the first-ever female US president.

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The latest national polls, released by CBS on Monday, gave Clinton a 4 percent lead over Trump in a four-way race that includes Green Party candidate Jill Stein and Libertarian Gary Johnson.

Race and immigration have been a major dividing factors in this election cycle.

And neither Clinton nor Trump has managed to gain a major foothold among voters of any of the minority communities across the US.

Election-day rallies

Both candidates have a full day of last-minuted rallies planned for Election Day on Tuesday.

Clinton will hold two events in Pennsylvania, one in Michigan and another one in North Carolina, while Trump is scheduled to be in Florida, North Carolina, Pennsylvania, New Hampshire and Michigan.

States such as Arizona, Florida, North Carolina, Virginia and Ohio have the power to swing the election.

These five major swing states, all of which are in eastern time zone in the US, and will be early indicators as to the winner of race.

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Source: Al Jazeera News And Agencies