Miami (AFP) - Hundreds of attorneys and volunteers from the presidential campaigns of Donald Trump and Joe Biden have deployed to Florida polling stations to make sure votes for their candidates are respected, as record numbers of people cast ballots early.

Tensions are especially high as fear about the coronavirus and violence at polling stations is compounded by Florida's history of contested elections that have ended in recounts or even court battles.

Florida, where Republican Trump and Democrat Biden are practically tied, accounts for 29 crucial electoral votes, with 270 needed to win the US presidency on November 3.

"We cannot trust those Democrats," said Cristiano Piquet, 43, a Republican and Brazilian-American who was casting his early vote at a Miami polling station while carrying a US flag. 

"They're pure evil and they are capable of anything. So I want to make sure that my vote counts," he told AFP, explaining why he voted early instead of by mail.

This is the type of fear that attorney Juan Carlos Planas - one of the 1,421 registered observers in south Florida's densely populated Miami-Dade County - wants to allay.

"There's never been a credible case of election fraud in the general election," Planas told AFP. 

He is a former Republican state representative who has observed elections previously - and this year is observing for the Democrats.

"Here there really isn't any sort of fraud or let alone massive fraud, it just doesn't happen," he said.

Florida's 14 million registered voters can vote by mail, a method widely used since 2002 and preferred by Democrats in part to keep people away from crowds and safe from the virus.

Trump, however, has made his distrust of the mail-in system clear -- even though he has voted by mail in the past in Florida, where he has his residence, and has said that Florida's mail-in system is trustworthy.

Floridians can also cast ballots in-person at an early voting station, like Piquet did, or on November 3, when Republicans are expected to vote in large numbers.

Tense environment

Florida's most memorable contested election occurred in 2000, when a mere 537 votes gave the state - and the presidency - to Republican George W. Bush over Democrat Al Gore.

In 2018 a recount was needed to confirm that the current governor, Republican Ron DeSantis, won.

Meanwhile in 2016, Russian intelligence hacked into the electoral system of at least one Florida county, according to the FBI.

Adding to the uncertainty are cases of voter intimidation.

The photo of a police officer in full uniform with a facemask emblazoned with "Trump 2020" at a polling station generated heated controversy on social media.

"We are aware of the photograph," the Miami Police Department tweeted. "This behavior is unacceptable, a violation of departmental policy, and is being addressed immediately."

As of Wednesday more than 2.95 million Floridians had voted by mail, state election officials said, surpassing the 2.73 million mail-in ballots in the 2016 presidential election with two weeks still to go.