US President Barack Obama and British Prime Minister David Cameron listen to a reporter's question during a joint news conference. Image Credit: AP

London: President Barack Obama on Friday bluntly urged Britain to vote to remain inside the European Union in a referendum scheduled for June 23, and warned that a Britain outside the bloc could not count on maintaining its current economic relationship with the United States.

Taking an unusually direct position on another country’s internal politics, Obama asserted that Britain’s membership in the bloc did not limit British influence but “magnifies it.”

Speaking alongside Prime Minister David Cameron at a news conference, he also directly addressed the potential consequences of a vote by Britain to leave. The president said that to do so would send Britain to the “back of the queue” for a trade deal with the United States, challenging those who have argued that Britain could quickly replicate the same favourable terms it enjoys as an EU member.

Cameron is leading the campaign to remain part of Europe, but the issue has divided his Conservative Party and polls suggest that the outcome could be close, making the forcefulness of Obama’s statements especially striking.

Obama was stating his view of US national interests, while also clearly trying to support Cameron. But the arguments here are increasingly bitter, and Obama was attacked as a hypocrite and worse by those who favour a British exit, or Brexit.

Obama defended the right of a close friend to give an opinion on a matter of mutual interest.

“Part of being friends is being honest, and, speaking honestly, the outcome of that referendum is a matter of deep interest to the United States, because it affects our interests as well,” he said.

Obama sidestepped a question on whether the “special relationship” between Washington and London would be damaged if Britain voted to leave the EU.

Nor did Obama comment on a suggestion by Mayor Boris Johnson of London, a leader of the campaign to leave the bloc, that the president was unfriendly to Britain because of his ancestry. Johnson, a Conservative, suggested on Friday that Obama removed a bust of Winston Churchill from the Oval Office because 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.”

Obama said he saw another bust of Churchill every day in the White House residence.

“I love the guy,” he said. But as the first African-American president, he said, he “thought it appropriate” to have a bust of the Rev. Martin Luther King Jr. in the Oval Office.

Cameron, for his part, smiled thinly and said that “questions for Boris are questions for Boris and not questions for me.”

The prime minister praised Obama for his friendship and “sage advice,” and said that Britain was made stronger through its continued membership in the EU and that “the stronger we are the stronger that special relationship” with the United States will be. Cameron noted that “it was hard to find any country that wishes Britain well that wants us to leave the EU,” and that Britons should listen to their friends and then vote as they choose.

Strong historical, emotional, cultural and security ties with Britain would continue no matter the vote, Obama said. But the United States, he said, was convinced that Britain made a shaky Europe stronger and more stable by its membership and that the bloc “enhances” Britain’s “influence and power and economy.”

He argued that the United States accepted constraints on its sovereignty, too, in multilateral institutions like Nato, the UN Security Council, the Group of 7 and Group of 20, and did so for the common good, which also was in US interests.

Earlier Friday, Obama and his wife, Michelle, travelled by helicopter to Windsor Castle for lunch with Queen Elizabeth II, who turned 90 on Thursday, and her husband, Prince Philip, 94.

The Obamas also had a private dinner Friday night with Prince William and his wife, Catherine, the Duke and Duchess of Cambridge, and Prince Harry at Kensington Palace in London.

Obama’s comments at the news conference underlined his argument, made in an op-ed piece published Friday in The Daily Telegraph, that Britain is stronger and more influential inside the European Union.

The president’s decision to wade into the issue during his two-day visit prompted objections from many supporters of the campaign to leave the EU. Nigel Farage, leader of the UK Independence Party, said that Obama should “butt out.”

One of the most polarising responses came from Johnson, who was born in New York and retains his US passport as a dual citizen. Johnson, who is also a member of Parliament and has ambitions to replace Cameron as prime minister, has argued that the United States is a traditional nation-state that would never transfer some of its sovereignty to any EU-like organisation.

“For the United States to tell us in the UK that we must surrender control of so much of our democracy — it is a breathtaking example of the principle of do-as-I-say-but-not-as-I-do,” Johnson wrote in The Sun newspaper, which is influential among working-class voters.

“It is incoherent. It is inconsistent, and yes it is downright hypocritical,” Johnson said.

On Twitter, Nicholas Soames, a Conservative member of Parliament and a grandson of Churchill, condemned Johnson’s essay, calling it “an appalling article” that is “totally wrong on almost everything.” It was “inconceivable,” Soames said, that his grandfather would “not have welcomed” the president’s views on Britain’s role in Europe.

A former leader of the Liberal Democrats, Menzies Campbell, said that “many people will find Boris Johnson’s loaded attack on President Obama’s sincerity deeply offensive,” and Diane Abbott, a Labour Party lawmaker, said that “Boris dismissing President Obama as ‘half-Kenyan’ reflects the worst Tea Party rhetoric.”

US officials suggested that there was an internal debate about the wisdom of the straightforward article Obama wrote in The Telegraph, but decided that it was better to be upfront about the president’s views as he arrived in Britain and not pretend to be coy.

Cameron clearly favoured a strong message from the president, whose position is shared by the leaders of Britain’s main European allies, France and Germany.

Britain and France are the two strongest military powers in Europe, and Britain is the second-largest economy in the EU and fifth largest in the world.

The economic risks of Britain’s exit from the EU are important to British voters, but so are immigration and the inability of Britain to limit the number of EU citizens who want to live and work here. While studies show that the immigrants contribute considerably more to the British budget in taxes than they receive in benefits, there are worries that the immigrants are taking jobs away from Britons.

These arguments are likely to be more important than those about Britain’s standing in the world or the country’s relationship with the United States.