New York, New York - Former US president Donald Trump celebrated the election of fellow populist Nigel Farage to Britain's parliament on Friday, neglecting to mention the new prime minister, Keir Starmer.

Farage's anti-immigration Reform UK party won the third largest vote haul, but under Britain's electoral system, it took just five seats while Starmer's Labour party swept into office with a landslide.

"Congratulations to Nigel Farage on his big WIN of a Parliament Seat Amid Reform UK Election Success. Nigel is a man who truly loves his Country!" Trump wrote on his Truth Social platform.

Farage is a long-standing ally of Trump, who has dubbed the divorced father-of-four "Mr. Brexit" and previously said the British populist would have done a "great job" as the UK's ambassador to Washington.

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Farage is a champion of Brexit who was elected to parliament on his eighth attempt and has made no secret of his desire to take over the now-main opposition Conservative party, which was trounced at the polls by Labour.

"There is a massive gap on the centre-right of British politics, and my job is to fill it," he said after a comfortable win in Clacton, eastern England.

The result bucks a rightward trend among Britain's closest allies, with the far-right National Rally in France eyeing power and Trump looking set for a return in the US.

Farage's win will likely embolden the attention-grabbing populist figurehead in his long-term aim of staging a "takeover" of the Conservatives.

Millions of their voters appeared to have already switched their support to Reform, handing the Tories one of their worst-ever results.

An initial exit poll caused a stir Thursday night after predicting Reform would secure 13 seats – far exceeding forecasts in the latter stages of the campaign that it would win just a handful.