LONDON (Reuters) - U.S. President Barack Obama told Britons on Friday he loved Winston Churchill, rebuffing suggestions that he had disrespected the wartime leader because of a grudge against Britain linked to his Kenyan ancestry.

London Mayor Boris Johnson speaks at a Vote Leave rally in Newcastle, Britain April 16, 2016. REUTERS/Andrew Yates

Obama was visiting London to press Britons to vote to stay in the European Union, and the Churchill issue arose after London Mayor Boris Johnson, who is campaigning for an “Out” vote, brought it up in an article criticizing Obama.

“I love Winston Churchill, I love the guy,” Obama said when asked at a news conference about Johnson’s article.

“Right outside the door of the Treaty Room, so that I see it every day, including on weekends when I’m going into that office to watch a basketball game, the primary image I see is a bust of Winston Churchill,” said Obama, referring to his private office on the second floor of the White House.

“It’s there voluntarily because I can do anything on the second floor,” he said, standing alongside Prime Minister David Cameron, who is leading the “In” campaign.

Obama did not name Johnson, but his remarks were a humiliating put-down for a man who is widely touted as a potential successor to Cameron, especially if voters do opt to leave the EU in a June referendum.

Johnson was accused of racist undertones by an opposition Labour politician over the opening paragraphs of an article he wrote in the Sun newspaper criticizing Obama’s stance on the EU.

In the passage, Johnson speculated about the reasons for the removal of a bust of Churchill from the Oval Office in 2009, during the early days of Obama’s presidency.

“Some said it was a snub to Britain. 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,” Johnson wrote in the mass-market Sun tabloid.

“APPALLING”

Obama’s father was Kenyan but the president does not hold Kenyan citizenship and has never lived in Kenya.

Johnson is not the first political opponent of Obama to try to make capital out of his family background. U.S. Republicans have done so for years, and the front-runner to win the party’s nomination for this year’s presidential race, Donald Trump, has been doing so during the campaign.

Johnson’s comment drew criticism from across the political spectrum in Britain, including from Conservative lawmaker Nicholas Soames, Churchill’s grandson, who called Johnson’s article “appalling” and “wrong on almost everything”.

“Inconceivable WSC (Churchill) would not have welcomed President’s views,” said Soames, who favors remaining in the European Union.

John McDonnell, the opposition Labour Party’s finance policy chief who also favors an “In” vote in the referendum, said Johnson’s comments contained an underlying hint of racism.

“Mask slips again. Boris part-Kenyan Obama comment is yet another example of dog-whistle racism from senior Tories (Conservatives). He should withdraw it.”

Asked during his news conference with Cameron to react to Johnson’s article, Obama drew laughs from reporters when he replied: “Let me start with Winston Churchill.”

He said his predecessor, George W. Bush, had kept a second bust of Churchill in the White House, this one in the Oval Office, but Obama had removed it to make space for one of Martin Luther King.

“I thought ... that as the first African American president it might be appropriate to have a bust of Dr Martin Luther King in my office to remind me of all the hard work of a lot of people who would somehow allow me to have the privilege of holding this office.”

Johnson responded to the criticism of his article by British politicians by saying he was “a big fan” of Obama.

In a statement sent by a spokesman, Johnson said the issue was the “weird paradox” of the president of a country that jealously guards its sovereignty urging Britain to surrender some of it by embedding itself further in the EU.