Donald Trump has suggested that the US election could be delayed over alleged fraud concerns relating to postal votes.

Trump raised the possibility of delaying the poll, which takes place the Tuesday after the first Monday in November every four years, in an appearance at the White House where he made unsubstantiated allegations that increased postal voting will result in fraud.

But can the 2020 election be delayed and does Donald Trump have such power?

What did Donald Trump say?

Earlier this week, Mr Trump said "universal mail-in voting" would make November's vote the "most inaccurate and fraudulent election in history" and a "great embarrassment to the USA. 

"The [Democrats] talk of foreign influence in voting, but they know that Mail-In Voting is an easy way for foreign countries to enter the race.”

He added postal voting was "already proving to be a catastrophic disaster" in areas testing the voting method. 

Addressing the subject yesterday, the president attempted to draw back his comments saying: "I don't want to delay, I want to have the election.

 "But I also don't want to have to wait for three months and then find out that the ballots are all missing and the election doesn't mean anything."

"I don't want to see a crooked election.

"This election will be the most rigged election in history if that happens."

In an address at The White House, he added: “You’re sending out hundreds of millions of universal mail-in ballots. Hundreds of millions.

“Where are they going? Who are they being sent to? You don’t have to know anything about politics.”

READ MORE: Donald Trump pulls back on his election ‘delay’ call amid backlash

Who can change the election date?

One of the major issues with Donald Trump calling for the election to be moved, is that he does not have the authority to move the date. By law, the US election is held on the first Tuesday after the first Monday in November. Any change of date would need to be approved by both houses of Congress - the House of Representatives and the Senate. Democrats control the House of Representatives and some have already said they will not support any delay to the vote.

Any move by Congress to delay the election into 2021 would also require a constitutional amendment. 

What are the concerns around postal voting?

There are concerns over posting votes, not only from what Donald Trump has said, but due to their current success in the US. This June, postal votes were used in the Democratic primary poll with long delays in counting the votes.

Other concerns include that many ballots will not be counted because they were not filled in correctly.

When is the US election?

The US election is part of the law of the country and must be held on the Tuesday after the first Monday in November in every fourth year — is enshrined in federal law and would require an act of Congress to change.

READ MORE: Donald Trump admits regrets over tweets

What States are considering postal votes?

California, Utah, Hawaii, Colorado, Oregon and Washington were set to use all mail votes in the elections this November. The states will automatically send postal ballots to all registered voters, which then have to be sent back or dropped off on election day. Some voting in booths will still be available with other states also considering the approach.