The number of postal votes for the US presidential election is expected to rise significantly this time round due to public health concerns over coronavirus.

Ellen Weintraub, commissioner of the Federal Election Commission, has said: “There’s simply no basis for the conspiracy theory that voting by mail causes fraud.”

There have been isolated cases of postal ballot fraud, such as in the 2018 North Carolina primary, which was re-run after a consultant for the Republican candidate tampered with voting papers.

There was also a case this year in New Jersey which saw two Democratic councilors charged with alleged fraud in relation to postal voting, after hundreds of ballots were found stuffed in a post box.

However, according to a 2017 study by Brennan Center for Justice, the rate of voting fraud overall in the US is between 0.00004% and 0.0009%.

According to a research by Charles Stewart, a political scientist at the MIT, postal ballots are more likely to go missing.

He calculated that the number of votes lost through the vote-by-mail system in the 2008 election may have been as many as 7.6 million, or one in five individuals who attempted to post their ballots.

All postal voting states still have in-person voting options for certain reasons.