Barack Obama has accused Donald Trump of trying to ‘kneecap the postal service’ in an attempt to stop people from voting.

The number of mail-in votes is expected to increase - seen as an advantage to the Democrats - as Americans will be less likely to vote in person due to the coronavirus pandemic.

However, the US Postal Service has warned mail-in votes may not be able to be counted in almost every state due to time and money.

The Democrats have proposed $3.6 million in election funding to help states with voting processing, with an additional $25m of funding for the postal service to meet the demand of the expected 180m mail-in votes.

But Trump has said he opposes the funding and has doubled down on his criticism of mail-in votes, advancing the idea that mail-in votes will benefit Democrat candidate Joe Biden and will lead to fraud.

He told Fox Business: "Now, they need that money in order to make the Post Office work, so it can take all of these millions and millions of ballots. That's election money basically.  

"If they don't get those two items, that means you can't have universal mail-in voting.

“If we don’t make a deal, that means they don’t get the money. That means they can’t have universal mail-in voting. They just can’t have it."

Biden called the remarks ‘pure Trump’ and said the President ‘doesn’t want an election’.

Hillary Clinton, who lost to Trump in 2016, encouraged Americans to get their ballots in as early as possible.

“Republican sabotage of the USPS, including slowing mail delivery, is a Trump strategy to make voting by mail more difficult this fall," Clinton said.

The US election will take place on November 3 and all postal votes will have to be turned in by that date or they will not be counted.