There's no precedent in modern politics for the sort of delay Trump is suggesting. The idea, floated in a series of tweets, prompted swift pushback from officials in both parties and much head-scratching.
A closer look at the key questions and answers about the president's extraordinary suggestion:
Will 2020 be the 'most inaccurate and fraudulent' election, as Trump says?
Time and again, voter fraud has proved exceedingly rare, and voting without going to polling places has become more common.
In fact, Trump's own 2016 presidential election victory came at the pinnacle of a decadeslong trend away from in-person voting on Election Day. Trump himself voted by mail in the Florida Republican primary.
Multiple checks, such as signature verification in many states, must happen before a ballot can be counted, and experts say any fraud can be detected. Voter fraud is often confused with election fraud. The latter is when a candidate, campaign worker or party official tampers with ballots to affect the outcome of an election.
Trump appointed a commission to get to the bottom of voter fraud after the 2016 election. The commission disbanded without any findings.
Many election officials and researchers believe that the greater threat to smooth U.S. elections is Americans' lack of confidence in the process.
Was mail voting a 'catastrophic disaster' in the primaries, as Trump says?
The coronavirus pandemic has certainly disrupted voting in this year's primaries. Some states delayed their elections, Many states limited the number of in-person voting stations and urged voters to vote by mail.
The late adjustments caused messes across the country, although not just with vote by mail.
Voters in cities such as Atlanta, Milwaukee and Las Vegas faced long lines after polling places were consolidated to deal with a dramatic decline in poll workers. Election offices, coping with their own staffing and budget constraints, were overwhelmed with a surge in absentee ballot requests.
As states complete their plans for November, many are preparing for a surge of mail-in voting that present new headaches. They'll have to add staff to open and process ballots. The U.S. Post Office must prepare for an increase in deliveries. Some states have had to change procedures on when to count votes. Election officials are warning the count will be slower.
Rather than seeking a delay, election officials are seeking federal money. Several have backed Democrats' effort to include election aid in a new virus relief package. The most recent proposal by Senate Republicans doesn't have money for those purposes.
Can Trump get the election moved?
Almost impossible. The date of the presidential election - 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. Democrats, who control the House, will not support Trump on this. It appears Republicans won't, either.
Senate Majority Leader Mitch McConnell, R-Ky., said after Trump's tweets Thursday that Election Day is set in stone. Other top Republicans were similarly dismissive.
Why is Trump talking about an election delay?
Some possible reasons: He's lagging in the polls against Democrat Joe Biden. He may be looking to distract people from his administration's failures in a pandemic that has killed more than 150,000 Americans and cratered the economy.
For all of his talk about fraud, Trump has been clear that he thinks mail-in voting helps Democrats. He was explicit on this point during negotiations for the coronavirus relief package in March, when Democrats proposed more money to expand vote by mail in the pandemic.
He said that with the levels of voting the aid would encourage, "you'd never have a Republican elected in this country again."
Is vote by mail an 'easy way' for foreign countries to interfere?
No. Contrary to Trump's tweet that "Mail-In Voting is an easy way for foreign countries to enter the race," it would be one of the most difficult ways for a foreign adversary to meddle in a U.S. election.
Swaying a federal election using absentee ballots would mean paying thousands of U.S. citizens, carefully selected in key cities in battleground states, who are willing to conspire with a foreign government and risk detection and prosecution.
Far easier and cheaper would be a social media campaign seeking to discourage certain groups of people from voting, something the FBI has already warned about. Or launching a sophisticated cyberattack on voter registration data that would eliminate certain voters from the rolls, causing havoc at polling places or election offices as officials look to count ballots from people who are "missing" from their voter databases.
Last month Attorney General Bill Barr raised the possibility that a "foreign country could print up tens of thousands of counterfeit ballots." He argued they would be hard to detect, but that's been disputed by election experts.
Absentee ballots are printed on special paper and must be formatted correctly in order to be processed and counted. Ballots are specific to each precinct, often with a long list of local races, and would be easily identified as fraudulent if everything didn't match precisely.
"This is a complete red herring," said Wendy Weiser, director of the democracy program at the Brennan Center for Justice. "It's completely not plausible, and not something that security and election experts are actually worried about."
Trump says universal vote by mail is bad and absentee ballots are 'good.' What's the difference?
Not much. Trump is trying to draw a distinction between the five states that send ballots to all registered voters and the other states, where voters must request an absentee ballot in the mail. He's not objected to absentee voting, which is the process that allows him to vote remotely in Florida.
But in both cases, voters must be registered to get a ballot and the actual method of voting is the same: Voters complete the ballot at their convenience before a deadline and can either mail it back to their local election office or drop it off at a designated location.
During the primary, voters in a small number of states that have historically required voters to request an absentee ballot opted instead to send ballots to them, because of the pandemic. Critics seized on sporadic reports of ballots being lost in the mail, found unsecured or sent to the wrong address. But that is not an indication that fraud actually occurred.