A historian who failed to predict the correct outcome of the 2024 election despite getting the right result in nine of the past 10 races has explained why he got it wrong.

Professor Allan Lichtman predicted that Kamala Harris would narrowly beat Donald Trump.

His predictions are based on his “13 keys to the White House” system, which has successfully determined the outcome of every election since 1984 aside from 2000, when he called it for Al Gore.

But speaking to CNN, Prof Lichtman said a multitude of factors played into the incorrect prediction, including the spread of disinformation and the way the Democratic Party’s campaign played out.

“I think the fundamental problem was the keys, not my interpretation, no one’s convinced me that was wrong,” he said.

“There are unique features, I’ve always said some unique features could break the patterns of history and I think that’s happened here.”

One feature was some Democrats “openly and viciously trashing” Joe Biden after his poor debate performance against Trump.

“I have never seen that before and I’ve studied politics since the founding,” he said. 

Biden’s plummeting approval rating in the debate’s aftermath “extended beyond” him to “weaken any Democratic candidate”, he said.

There was also an “explosion” in trends that have existed before, “but not to this extent”, Prof Lichtman said.

“Disinformation – you know, Elon Musk… has been the director of misinformation, two billion views of his spreading of disinformation, not just about the economy but about immigrants, about minorities. We’ve never seen disinformation at this scale,” he said.

He also said there was an “agitation” of three trends “deeply embedded in American history” – misogyny, racism and xenophobia – that had never been seen before.