US President Donald Trump has raised the idea of delaying the November 3 election, an idea immediately rejected by both Democrats and his fellow Republicans.

Critics and even Mr Trump’s allies dismissed the notion as an non-serious attempt to distract from devastating economic news.

Tweet from @realDonaldTrump

However some legal experts warned that Mr Trump’s repeated attacks could undermine his supporters’ faith in the election process.

Mr Trump’s earlier statement on Twitter came as the US endures the greatest crises of a generation: a coronavirus pandemic that has claimed more than 150,000 lives, a crippling recession sparked by the outbreak, and nationwide protests against police violence and racism.

On Thursday morning, the government reported the worst US economic contraction since the Great Depression: 32.9 per cent in the second quarter.

Mr Trump, who opinion polls show trailing Democratic challenger and former vice president Joe Biden, said he would not trust the results of an election that included widespread mail voting – a measure that many observers see as critical given the coronavirus pandemic.

Without evidence, he claimed that mail voting would be rife with fraud.

“With Universal Mail-In Voting (not Absentee Voting, which is good), 2020 will be the most INACCURATE & FRAUDULENT Election in history. It will be a great embarrassment to the USA,” Mr Trump wrote on Twitter on Thursday.

“Delay the Election until people can properly, securely and safely vote???”

With Universal Mail-In Voting (not Absentee Voting, which is good), 2020 will be the most INACCURATE & FRAUDULENT Election in history. It will be a great embarrassment to the USA. Delay the Election until people can properly, securely and safely vote???

— Donald J. Trump (@realDonaldTrump) July 30, 2020

The US Constitution gives Congress the power to set the timing of elections.

Multiple congressional Republicans – including Senate Majority Leader Mitch McConnell and top House of Representatives Republican Kevin McCarthy – rejected the idea.

“Never in the history of the federal elections have we ever not held an election and we should go forward with our election,” Mr McCarthy said.

Democratic US Representative Zoe Lofgren, who chairs the House committee overseeing election security, rejected any delay.

“Under no circumstances will we consider doing so to accommodate the President’s inept and haphazard response to the coronavirus pandemic, or give credence to the lies and misinformation he spreads,” Ms Lofgren said in an email to Reuters.

Mr Trump wrote on Twitter later on Thursday that Americans needed to know the election results on the night of the voting, not days or months later.

Mail-in ballots can sometimes take longer to count.

“Glad I was able to get the very dishonest LameStream Media to finally start talking about the RISKS to our Democracy from dangerous Universal Mail-In-Voting,” he tweeted.

The truly dangerous part of Mr Trump’s tweet on Thursday was not his suggestion of delaying the election – which is a “fantasy” – but his latest claim that voting by mail is rife with fraud, according to Justin Levitt, a professor at Loyola Marymount University and a constitutional law expert.

“This is yet another example of the president seeking to delegitimise the election process before it happens,” Mr Levitt said.

“That is deeply destabilising.”

-AAP