Trump accused the UK’s ruling Labour Party of “blatant foreign interference” and illegal foreign campaign contributions to Democratic presidential candidate Kamala Harris’ campaign, in a filing with the Federal Election Commission earlier this week.

Starmer denied that the legal complaint would impact his relationship with Trump, who he met for the first time over a two-hour dinner in New York last month. “We had a good, constructive discussion and, of course as prime minister of the United Kingdom I will work with whoever the American people return as their president in their elections which are very close now,” Starmer said.

The filing by Trump’s campaign is unlikely to gain traction; campaigns routinely meet with representatives of foreign governments and foreign nationals are permitted to serve as campaign volunteers as long as they are not compensated for their work, according to US campaign rules.

Trump’s complaint points to a social media post by a Labour Party official saying nearly 100 current and former staff members planned to travel to battleground states in the US to campaign on the vice president’s behalf.

A number of Starmer’s senior advisers including his now chief of staff Morgan McSweeney attended the Democratic National Convention in August to impart their election-winning strategy to Harris’s team, Bloomberg reported last month. The Democrats didn’t pay for his visit, Labour said.

Labour Party volunteers “have gone over pretty much every election,” Starmer told reporters on his way to the Commonwealth heads of government meeting in Samoa. “They’re doing it in their spare time, they’re doing it as volunteers, they’re staying with other volunteers over there.”

The Democrats and the UK’s Labour Party have long been ideological bedfellows, and for decades have exchanged advice and advisers, including Democratic strategist Bob Shrum who went on to advise Labour former Chancellor and Prime Minister Gordon Brown. Shrum told Bloomberg last month that there’s been “cross-pollination between progressive strategists in the US and the Labour Party” for the past 30 years.

Still, the flap offers Trump — who faced a special counsel investigation in his first term that ultimately concluded there was not evidence he had coordinated with Russian electoral interference activities, and whose recent partnership with billionaire Elon Musk has prompted campaign finance questions — the opportunity to go on offense on issues Democrats have used to criticize him.

Trump’s campaign said it believes “foreign nationals are exercising direction and control over elements of the Harris campaign” marked by “similarity in messaging” between the two campaigns. British and American voters share concerns on immigration, housing and the economy, though debate over the right to an abortion — a key feature of the US campaign — has long been absent from British politics.

“The flailing Harris-Walz campaign is seeking foreign influence to boost its radical message – because they know they can’t win the American people,” Trump campaign co-manager Susie Wiles said in a statement.