LONDON — Nigel Farage and a group of opposition politicians are trying to turn the U.S. Trump administration against a key but controversial piece of British foreign policy — and the U.K. government is furious.

The fight centers around the U.K.’s plan to cede sovereignty of the Chagos Islands to Mauritius, in a deal that had been signed off by President Donald Trump and PM Keir Starmer directly — but was unexpectedly thrown into question last week after Trump publicly called the move “stupid.”

British diplomats are now racing to ensure the U.S. won’t stand in the way of London’s plan. But Washington has for months been receiving representations urging just the opposite from Farage — leader of Britain’s populist-right Reform UK party — and a host of other opposition politicians, according to individuals involved in the dual campaign.

The highly unusual gambit has triggered anger inside the Foreign Office, the Ministry of Defence and beyond. And it has raised questions over whether a deal London thought was secure will now be sent back to the drawing board.

“Failing to understand the national security implications of this, while pursuing a deliberate political campaign for individual interests, is incredibly dangerous,” said one senior defense official, who like others in this piece was granted anonymity because they weren’t authorized to speak publicly.

‘Great stupidity’

The White House’s backing for the Chagos deal is crucial because the British territory of Diego Garcia in the Indo-Pacific hosts an important U.S.-U.K. military base. Britain had been sure the White House was supportive of an agreement that would ensure the facility remains open while ending long legal wrangling with Mauritius. 

Trump had publicly indicated support for the deal in the past. Top administration officials Marco Rubio and Pete Hegseth did so explicitly.

Then came last week’s Truth Social broadside from Trump at what he argued is an “act of GREAT STUPIDITY” that would embolden Russia and China. His post alluded to Greenland as well, and Starmer himself said he believed the move was retaliation for the British prime minister’s opposition to Trump’s threats to capture the Danish territory.

The turnabout followed a fierce campaign of opposition to the deal from members of the British right, even before the agreement was formally signed in May last year. 

It was a Conservative government that agreed to open negotiations with Mauritius over the future of the islands back in 2022. The U.K. retained possession of the archipelago after the former colony gained independence in 1968 — but international court rulings have gone the way of Mauritius winning sovereignty in recent years.

But British Conservatives, who are staunchly against the “surrender” of British territory (including former Boris Johnson aide Ross Kempsell), had been exerting pressure on Pentagon and State Department officials, as well as Republicans on the Hill and D.C. think tanks, according to one Conservative MP involved.

Separately, Farage was also working his U.S. contacts. A Reform official said Farage had pressed the case with the president at two in-person meetings late last year. One was in the Oval Office in September, the other at an event in Mar-a-Lago in November, they said.

White House spokesperson Anna Kelly did not directly respond to questions about the content of those conversations and referred POLITICO to Trump’s Truth Social post and recent remarks to journalists criticizing the Chagos deal.

Farage also brought up the deal — which he has labeled an “act of treachery” — with administration officials including Vice President JD Vance and Hegseth late last year, according to the same Reform official.

Conservative Party leader Kemi Badenoch has long campaigned against the deal in Britain, and one of her aides said they believed raising the islands with Speaker Mike Johnson during his own visit to the U.K. earlier this month played a role in Trump’s shift.

The (official) British response

Starmer responded by hardening his language toward a president he has been at pains to keep onside. 

Behind the scenes Britain mounted a calm response through diplomatic channels, first to understand the true nature of Trump’s outburst and then to get America back on board.

Two U.K. officials indicated they effectively had to start from scratch in explaining the security implications were Britain to have lost the islands in legal battles with Mauritius. It was an argument they thought they’d won early last year after it was signed off after extensive consideration by the White House, the State Department and the Pentagon.

One of the senior British government officials quoted above said: “We’re having daily conversations with American officials. Ultimately we will continue to communicate with our American partners and we’ve always said this deal won’t go through if the U.S. doesn’t agree — that still is a fundamental.”

Privately, figures across the British government suspect Trump has misunderstood the deal. They point to his comments in a White House press conference as he pondered Britain’s motive: “Do they need money?” he queried. In fact Britain will pay Mauritius around £3.4 billion over the initial 99-year lease so the joint base in Diego Garcia can stay open.

Opposition operations persist

While Britain makes its official representations, Trump’s administration is meanwhile being lobbied in the opposite direction. Starmer seemingly did not raise Chagos with Trump in their call on Saturday, with no mention in a British readout of the call.

But Farage used his visit to the World Economic Forum last week to press U.S. Treasury Secretary Scott Bessent on the agreement. Farage came away from Switzerland boasting that Bessent had agreed the deal is “not in our interests” and that America is “not going to put up with it.” 

The rival Conservatives, meanwhile, have been trying to thwart legislation associated with the agreement from making its way through the U.K. parliament. The government had to pull a debate in the House of Lords scheduled for this Monday because of a “wrecking amendment” laid by the Tories. 

Labour whips are working to win backing from other factions and insist the bill should return within weeks — but the delay has won diplomatic attention. 

The Tory MP lobbying against the deal cited above said that Washington’s ambassador to London, Warren Stephens, is sympathetic to their cause, and was in contact with their operation earlier this week. “Ambassador Stephens is in constant contact with U.K. policymakers across the spectrum on a full range of issues,” a spokesperson for the U.S. Embassy in London said when pressed on that claim.

An American official familiar with the discussions acknowledged that there are “differing perspectives and differing U.K. interests pushing their sides.”

Anger in government

Foreign policy experts said the situation — Farage and the Conservatives pushing hard against the official position — is an oddity in the British system.

“It is highly unusual for a U.K. political party to be lobbying a foreign government over a U.K. foreign policy decision,” said Evie Aspinall, director the British Foreign Policy Group. “In part, that is because foreign policy is often relatively bipartisan, and because it is widely accepted that issues of national security should be addressed on a government-to-government basis.”

Experts struggled to point to similar cases in recent history. After being dumped out of office in 2022, Boris Johnson did routinely press for a harder line from Western powers in support of Ukraine. But that was always in the same direction as the government, typically urging them to go further and faster. 

Aspinall suggested that the Chagos deal represents an “opportunity” for Farage to bolster his long-standing relationship with Trump “without alienating” voters wary of the U.S. president. Polling suggests that the hard-to-explain deal is deeply unpopular in the U.K.

In a sign of the anger in government, a senior Downing Street aide said of the Reform UK Chagos pushback: “Nigel Farage has shown time and time again that he is not on the side of the British people.”

The Reform official quoted above shot back: “We are keeping up the pressure on the U.S.”

The Foreign Office, meanwhile, is doing some contingency planning in case Trump does side against Starmer.

That scenario would not only be a deep rebuke of the PM’s transtlantic strategy — it could leave Britain in a world of legal pain too. Mauritius has driven a hard bargain over the base and may still demand payment, while resuming its legal action to gain full sovereignty.

Esther Webber contributed to reporting.