In a forthright intervention into the debate over Britain’s future in Europe, the US president made clear that in the event of a Brexit, any prospective deal would not happen “any time soon”, The decision to go it alone, he added, would curtail the nation’s standing on the global stage and its long-standing relationship with the US.
He said that Britain’s EU membership “magnifies the power of the UK, it doesn’t diminish it,” and stressed that the country’s prospects were best served by remaining in the union.
Quoting John Donne, Mr Obama said: “I think there’s a British poet that once said, ‘No man is an island,’ even an island as beautiful as this. We’re stronger together.” His remarks at a joint press conference with Prime Minister David Cameron represent one of the most significant developments in the EU referendum debate so far and represent a major blow to pro-Leave campaigners who insist Britain’s economy would not be affected should the vote go their way.
Earlier this week, justice secretary Michael Gove said a UK outside of Europe would still be able to arrange trade deals with the US, China and India.
But speaking at the Foreign Office, Mr Obama warned any such arrangement would not be a US priority, with Washington’s focus trained on reaching an agreement with the “bigger bloc” of trading partners in the EU.
“Maybe at some point down the line there would a US-UK trade agreement but it wouldn’t happen any time soon,” he added.
Mr Obama emphasised that his opinion should not be regarded as a “threat,” but should instead “enhance” the debate in the lead up to the June referendum.
He said that the referendum was a “decision for the people of the United Kingdom” and he was “not coming here to fix any votes.” However, he said that he wanted to take the opportunity to address certain arguments emerging from the Leave camp.
“Some of the folks on the other side have been ascribing to the United States certain actions we will take if the UK does leave the EU – they say for example that ‘we will just cut our own trade deals with the United States’,” he explained.
“So they are voicing an opinion about what the United States is going to do. I figured you might want to hear from the president of the United States what I think the United States is going to do.”
Mr Cameron, who at several points nodded and smiled during Mr Obama’s address and question and answer session, told the press conference that it “makes sense to listen to what our friends think” and that being a member of the EU strengthened Britain’s “special relationship” with the US.
The conference came after Mr Obama wrote an article for a daily newspaper in which he made an unexpectedly emotive play for Britain’s continued EU membership, an issue that was, he said, of “deep interest” to his country.
He wrote: “The tens of thousands of Americans who rest in Europe’s cemeteries are a silent testament to just how intertwined our prosperity and security truly are.”
The article, which largely dispensed with diplomatic niceties, argued that the relationship between the US and UK had been “forged as we spilt blood together on the battlefield”. In the present day, it added, the UK’s prospects in terms of employment, trade and financial growth were improved by its EU membership, a status that “magnifies” its global influence.
Mr Obama warned: “In this complicated, connected world, the challenges facing the EU – migration, economic inequality, the threats of terrorism and climate change – are the same challenges facing the United States and other nations.
“And in today’s world, even as we all cherish our sovereignty, the nations who wield their influence most effectively are the nations that do it through the collective action that today’s challenges demand.”
The article prompted a backlash from those campaigning for a Brexit. Boris Johnson said Mr Obama’s stance was “hypocritical” given the structure of the EU was “alien” to US traditions.
The London mayor also became embroiled in controversy for referring to Mr Obama’s “part-Kenyan” ancestry in an article for a tabloid newspaper which suggested he may have an “ancestral dislike of the British Empire” due to his heritage.
He also recounted a claim that a bust of Winston Churchill was removed from the Oval Office after Mr Obama was elected and returned to the British Embassy.
Mr Johnson said the move “was a symbol of the part-Kenyan president’s ancestral dislike of the British Empire, of which Churchill had been such a fervent defender”.
Ukip leader Nigel Farage later agreed, insisting that “because of his grandfather and Kenya and colonialisation, I think Obama has a bit of a grudge against this country”.
Mr Johnson’s comments were roundly condemned by his political opponents, with former Liberal Democrat leader Menzies Campbell describing the “attack” as “an unacceptable smear”.
Shadow chancellor John McDonnell accused him of “dog whistle racism,” while former British permanent representative to the EU Sir Stephen Wall said the comment was “demeaning to the debate”.
Asked to address Mr Johnson’s article, Mr Obama said he “loved” Winston Churchill, but said “there are only so many tables” in the Oval Office to accommodate busts before it starts to “look a little cluttered”.
Mr Cameron said the “questions for Boris are questions for Boris... not for me.”
Earlier, the two men held talks for around an hour and 45 minutes at Downing Street, where they discussed issues such as the progress made in combating Islamic State in Iraq, the response to Moscow’s actions in the Ukraine, and the formation of an international anti-corruption co-ordination centre.
Mr Obama and his wife, Michelle, were to be guests at a dinner at Kensington Palace last night with the Duke and Duchess of Cambridge and Prince Harry.
This evening, Mr Obama and Mr Cameron will attend a private dinner hosted by US ambassador Matthew Barzun at his official residence Winfield House, in Regent’s Park.