WASHINGTON, United States (AFP) — State law enforcement officials warned Monday against pressure to declare the winner of the US election, amid reporting that President Donald Trump has mulled claiming victory before votes are counted.

“States do not certify the election on election night,” Michigan Attorney general Dana Nessel told reporters. “We’re not about to let anyone steal this election.”

“We have experience in handling close elections,” Josh Stein, the attorney general of North Carolina, said in a briefing organised by the non-partisan Voter Protection Project.

“We may know the winner Tuesday night … or we may not know the winner,” he said.

If Trump declares victory prematurely, he added, “it would be unfortunate, but it really would be irrelevant.”

The political news website Axios reported Sunday that Trump has told confidants he will declare victory right away late Tuesday if it looked like he was ahead in the voting.

But officials in many states, such as Michigan, Wisconsin, and Pennsylvania — all key states where the outcome is unpredictable — have said that counting the large numbers of mail-in votes could take at least another day and perhaps three days.

Wisconsin Attorney General Josh Kaul said that because counting mailed ballots cannot begin in his state until Tuesday, it could easily take until Thursday for a result.

Trump called the Axios claim a “false report.”

But, he added, “I don’t think it’s fair that we have to wait for a long period of time after the election,” and said the Republicans were going to “send in the lawyers” to challenge late results.

Republicans suspect that mailed ballots will largely favor his Democratic rival Joe Biden, and Trump has repeatedly claimed that late-arriving mailed votes not counted on Tuesday will be suspect and possibly fraudulent.

But the White House has not offered any evidence to support his claim.

Grant Woods, former attorney general of Arizona and an advisory board member of the Voter Protection Project, called perennial claims of significant voter fraud “a myth.”

“It’s become the Republican version of Bigfoot,” he said, a mythological creature many people have heard of but whose existence has never been proven.

“The voters will decide this, not the politicians. Nobody is going to steal this election,” he echoed.