The FBI is launching an investigation into reports that voters received automated phone calls telling them they should delay their vote until tomorrow.
Fake messages urging people to stay at home because of long queues were reported in several states.
Dana Nessel, the Attorney General of Michigan, a swing state, said she received reports of automated calls to residents that falsely claimed people should vote after polling stations closed.
Earlier on Tuesday, The National reported people were flocking to vote in the state.
The Washington Post reported that the FBI had begun an inquiry in Michigan after millions of calls were received across the US.
Audio of the calls features a synthetic female voice saying: “Hello. This is just a test call. Time to stay home. Stay safe and stay home.”
A senior Cybersecurity and Infrastructure Security Agency official described it as “a voter-intimidation, voter-suppression tactic”.
The Attorney General for New York, Letitia James, said her office was also investigating the issue.
“Voting is a cornerstone of our democracy,” Ms James said.
“Attempts to hinder voters from exercising their right to cast their ballots are disheartening, disturbing and wrong. What’s more is that it is illegal and it will not be tolerated.”
The calls were also reported in Kansas, where the Secretary of State posted a message on Facebook urging people to still vote.
“We are receiving reports of robocalls telling voters to stay home,” Scott Schwab wrote.
“Disregard these calls. If you have not already voted, today is the day.”
The US public appears to have heeded his advice with queues of voters snaking round polling stations throughout Tuesday.
More electoral skulduggery
Further election mischief emerged after Republican activists shared an Instagram story of someone claiming to be an election worker throwing out ballots from Donald Trump supporters in Erie county, Pennsylvania.
The post was a hoax, a spokeswoman for Erie county said . “He is not one of our poll workers and there is no one with that name registered to vote in Erie PA,” Amy Dalessandro, the election co-ordinator, said.
A Trump supporter who shared the image had her account temporarily limited and was unable to post for violating rules against posting misleading information about voting.
