Joe Biden has suffered “the worst day of his presidency”, an ally said, after a bombshell report found the US President had “significant limitations in his memory”.

Lawyers who interviewed Mr Biden as part of an investigation into his handling of classified documents said he could not remember the years when he was vice president or when his son died of brain cancer.

An ally of the President said it had been “the worst day of his presidency”, telling NBC News: “I think he needs to show us this is a demonstrably false characterisation of him and that he has what it takes to win and govern.”

Another Democratic operative said the report was “beyond devastating” and “confirms every doubt and concern” that voters have about Mr Biden.

“If the only reason they didn’t charge him is because he’s too old to be charged, then how can he be President of the United States?” they added.