The domestic debate over whether the United Kingdom should leave the European Union has grown into a trans-Atlantic one.

U.S. President Barack Obama, who landed in London late Thursday, kicked off his visit to the country with a call for the U.K. to remain in the European Union rather than pull out in a so-called Brexit, on which Brits are slated to vote June 23. And anti-EU politicians are vocally unhappy about Obama's interjection.

"For the United States to tell us in the U.K. 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,'" London Mayor Boris Johnson, a staunch pro-Brexiter, wrote in the Sun on Thursday. "The Americans would never contemplate anything like the EU, for themselves or for their neighbors, in their own hemisphere. Why should they think it right for us?"

In comments published Thursday in the U.K.'s Daily Telegraph upon his arrival in the country, Obama acknowledged that the question of a Brexit is "a matter for British voters to decide for yourselves." However, he added, "you should be proud that the EU has helped spread British values and practices — democracy, the rule of law, open markets — across the continent and to its periphery. The European Union doesn’t moderate British influence — it magnifies it."

"A strong Europe is not a threat to Britain’s global leadership," Obama wrote, listing ways the U.K. had benefited from its membership in the European Union. "It enhances Britain’s global leadership."


Others besides Johnson have similarly taken umbrage at Obama's comments.

Iain Duncan Smith, former secretary of work and pensions, also described Obama's support for Britain to remain in the EU as hypocritical, because the U.S. would never relinquish sovereignty to a body like the EU the way Obama is urging. Duncan Smith is a prominent Brexit supporter.

“I have a huge amount of respect for America’s unrelenting commitment to the patriotic principle of self-governance. President Obama, and every one of his predecessors, have ferociously protected the sovereignty of the USA,” Smith said.

But Alan Johnson, head of the campaign Labour In for Britain, said Obama had every right to comment and endorse one outcome over the other. In fact, "I believe he has an obligation to point out the wider ramifications of a British withdrawal from the EU," he said.

Meanwhile, the British pound showed signs of recovery against the euro this week, consistently rising against the continental currency to trade Friday at 0.783 British pounds to the euro.

During his visit, Obama is expected to meet with Prime Minister David Cameron, who has pledged his "heart and soul" to staying in Europe, to discuss a slew of issues, including destroying the Islamic State militant group and creating political stability in the Middle East. Obama is scheduled to participate in a town hall event Saturday where he is expected to field questions from attendees about his views on the June vote.