Washington. Americans go to the polls today to elect the 45th president of the United States, capping a historically divisive campaign.

White House rivals Hillary Clinton and Donald Trump duelled yesterday for a handful of must-win states in an end-game election frenzy.

It was unclear whether the Democrat could convert into electoral gain the announcement Sunday that the FBI had cleared her again of wrongdoing over her email use.

Mrs Clinton’s popularity had dipped after FBI Director James Comey dropped a campaign bombshell eight days earlier with a reopened inquiry into whether she exposed US secrets by using a private email server while serving as secretary of state.

Opinion polls had tightened as Mr Trump began to recover ground lost while battling accusations of sexual assault, and the race looked headed for a photo finish.

The billionaire Republican contender, who has whipped up a populist grassroots movement among largely white male voters, landed in Sarasota, Florida early yesterday and was met by an enthusiastic crowd.

After a stop there, the 70-year-old was due to fly to rallies in North Carolina, Pennsylvania, New Hampshire, before ending with a late event in Michigan.

In Virginia Sunday, he stoked supporters at a post-midnight rally with stock attacks on his rival, branding her the “most corrupt candidate ever to seek the office of the presidency.”

Mrs Clinton, 69, had events planned through midnight yesterday, with stops in Pennsylvania, Michigan, and North Carolina. The rallies will include appearances by a star-studded roster of supporters headlined by President Barack Obama and rock star Bruce Springsteen.

Mrs Clinton’s Sunday rallies had a note of optimism mixed with warnings of the threat posed by Mr Trump.

“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 aghast as Mr Trump’s sensationalist reality television style became a driving force propelling him toward the most powerful political post in the world.

Global financial markets were rocked when the renewed FBI probe threatened to sink Mrs Clinton’s chances, and were boosted by news of the FBI’s closure of the affair. Asian and European exchanges jumped yesterday morning, hours after the announcement.

But commentators said renewal of the email scandal, which dominated one of the last news cycles ahead of the election, had already damaged the Democratic former first lady’s chance of succeeding Mr Obama.

Mrs Clinton’s lead dropped from 5.7 to 2.9 percentage points in the week since the scandal returned, according to influential data website FiveThirtyEight.com.

Mr Trump is predicting a ballot upset on par with Britain’s shock vote to quit the European Union, or what on Sunday he called: “Brexit plus, plus, plus.”

“The rank and file special agents of the FBI won’t let her get away with her terrible crimes,” Mr Trump told a rally in Michigan, a state Mr Obama won comfortably in 2012.

For Mr Trump and his supporters, Mrs Clinton symbolizes the corruption of the Washington elite.

“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!”

Mr Trump has repeatedly condemned Mrs Clinton’s “criminal scheme” and argued that she’s unfit to be president.

He has previously threatened to reject the result of today’s vote if he loses, alleging that the race has been “rigged” by the media and the establishment elite. (AFP)