Keir Starmer has offered Donald Trump ‘hearty’ congratulations for his stunning election win as he scrambles to smooth over tensions

The PM paid gushing tribute in a phone call last night, including ‘fondly’ reminiscing about an introductory dinner they had in New York in September

Photos show Sir Keir using a mobile phone to speak to Mr Trump

He branded Mr Trump a ‘Neo-Nazi sympathiser’ and a ‘tyrant in a toupee’, with Republican commentators warning that the president-elect will remember the slight.

The PM has also repeatedly clashed with billionaire Elon Musk, who looks certain to end up playing a key role in the Trump administration.

Sir Keir could now face a choice between allying more closely with the EU, or fostering tighter ties with the US – Britain’s biggest single trading partner.

Mr Trump is threatening huge tariffs on global imports to America, but had pledged to do a Transatlantic free trade deal with the UK when he was last in power.

One senior minister described Mr Trump’s return as a ‘nightmare’, adding: ‘We are going to have to deal with a whole new world order.

‘Whether you look at defence or trade or Ukraine or climate change, everything is going to change in ways that are unpredictable and difficult to navigate.’

No10 said Sir Keir congratulated Mr Trump on his ‘historic victory’ after US voters returned him to the White House.

‘The Prime Minister offered his hearty congratulations and said he looked forward to working closely with President-elect Trump across all areas of the special relationship,’ the readout said.

‘The leaders fondly recalled their meeting in September and President-elect Trump’s close connections and affinity to the United Kingdom, and looked forward to working with one another,’ No 10 added.

Former shadow chancellor John McDonnell has urged Sir Keir to move further to the Left, saying: ‘The key lesson of the Trump victory for us is that Labour has to deliver the significant improvement in quality of life that people can feel or we face the rise of right wing populism that has swept America. Half measures won’t be enough.’

But Nigel Farage, who has close links to Mr Trump, said the PM must ‘roll out the red carpet’.

Foreign Secretary David Lammy previously called Trump a ‘neo-Nazi’ sympathiser

Sir Keir faced anger from Republicans after around 100 Labour activists and MPs went to campaign for Kamala Harris (pictured)

Cabinet Office minister Pat McFadden dismissed the Reform leader’s offer to act as a bridge to the president-elect.

And he insisted that Mr Trump could see past previous swipes at him, including by his own vice-president elect JD Vance.

‘Look, a lot of people said things about Trump, not least his vice president, who mused whether Trump would be another Richard Nixon or America’s Hitler,’ he said.

‘If president-elect Trump held a grudge against everybody who’d said mean things about him in the past, he wouldn’t be talking to his vice president…

‘So these things have been said. But when it comes down to it, the alliance between the United Kingdom and the United States is very strong.

‘It’s very deep. It’s enduring. And we look forward to a good working relationship with the new president.’