WASHINGTON — The day after Britain voted to exit the European Union in 2016, Donald J. Trump landed in Scotland and promptly declared the referendum result “a great thing.”
More than two years later, President Trump is back in Britain, and now he wants to speed it along.
With its push to restrict immigration and its appeal to “take our country back,” the Brexit campaign was always a close political relative of the Trump movement in the United States. In many ways, it was a precursor to Mr. Trump’s election — which Stephen K. Bannon, the president’s former political adviser, often called “America’s Brexit.”
By his own admission, Mr. Trump is no scholar of Brexit. “I don’t think anybody should listen to me because I haven’t really focused on it very much,” he said in an interview with Fox Business Network days before Britain’s referendum on June 23, 2016. “But my inclination would be to get out, you know, just go it alone.”
Yet in the eyes of many of Mr. Trump’s aides and supporters, Brexit helped validate and legitimize the nationalistic “America First” ideas on which Mr. Trump’s campaign was built. It supported his notion that the world is a stage on which great powers compete — and strike the best deals possible — while bending weaker countries to their will.
British advocates of Brexit have long harbored ambitions not just to fragment the European Union but to wreck it. It is an ambition that Mr. Trump has often appeared to support, casting the European Union as an economic competitor that has stymied American farmers with its limits on genetically modified produce, hormone-treated beef and chlorine-washed chicken.
On Friday, Mr. Trump again condemned the European Union’s trade policies and what he called their “barriers beyond belief” that lock American products out of their market.
His desire for Britain to distance itself from these rules — and therefore to open itself to increased trade with the United States — was at the heart of an interview the president gave to The Sun newspaper a day earlier, immediately placing himself at the center of British political struggle.
In the interview, which was published hours after he arrived in London, Mr. Trump signaled his support for hard-line Brexit backers who want a clean break with the European Union. That put him at odds with Prime Minister Theresa May of Britain, who is pushing a business-friendly approach that would preserve many economic ties to the bloc.
Though Mr. Trump sought on Friday to play down his criticism of Mrs. May, his remarks about Brexit highlighted the close connections he has enjoyed with those who first championed the idea of Britain leaving the European Union — and who are now the prime minister’s ardent opponents.
Among them is Nigel Farage, a strident crusader against the European Union. He helped push the Brexit campaign, and…