The US President is on a state visit to the UK in support of EU campaign
London Mayor Boris Johnson has come under fire for referring to the US President as "part-Kenyan" in an article on the American leader's opposition to the UK leaving the EU.
He made his comments in The Sun newspaper, attacking Barack Obama over his intervention in the campaign ahead of the EU referendum.
Mr Obama used an official visit to the UK, during which he is meeting the Royal family and members of David Cameron's Government, to evoke the bond between the countries since World War Two in a bid to stop the country voting to leave the EU on June 23.
In his article on the President's visit, Johnson referred to Mr Obama removing of a bust of Winston Churchill from the Oval Office and stated that: "Some said it was a symbol of the part-Kenyan president's ancestral dislike of the British empire - of which Churchill had been such a fervent defender."
His imperial comments drew anger from those on the same as well as opposing sides, with some on social media describing them as "racist".
Labour's shadow chancellor John McDonnnell tweeted: "Mask slips again. Boris part-Kenyan Obama comment is yet another example of dog whistle racism from senior Tories. He should withdraw it."
Fellow Labour frontbencher Diane Abbott said that Mr Johnson's comments were "offensive" and channeled the Tea Party tendencies in the US.
Former Lib Dem leader Menzies Campbell said Johnson's comments were "an unacceptable smear", adding: "If this is an illustration of the kind of diplomacy that we might expect from a Johnson leadership of the Tory Party then heaven help us".
And ex-UK ambassador to Washington John Kerr said: "The US has an interest in Britain, its closest ally, being stronger, safer and better off in the EU".
"To claim that the American president has no right to say what he believes...is typical Boris bluff and bluster".
Tory MP Nicholas Soames - the grandson of Winston Churchill - said Mr Johnson was being "even more unreliable and idle about the facts than usual".