British Prime Minister Sir Keir Starmer has offered Donald Trump ‘hearty’ congratulations for his election win as he desperately attempts to smooth over tensions following what has been described as his party’s interference in the US election.

Critics argued the move amounted to foreign election interference after “nearly 100” current and former Labour party staffers headed to the US to help Kamala Harris during the final stretch before the election.

On Wednesday night the UK’s hypocritical leader paid his gushing tribute to Trump in a phone call during which he also ‘fondly’ reminisced about an introductory dinner they had in New York in September.

The Mail Online reports: The PM is facing a huge challenge after tensions flared over Labour supporters helping to campaign for Democrat contender Ms Harris. It sparked the Republican’s campaign team to file a legal complaint with accusations of ‘foreign interference’.

Tories are also demanding Sir Keir apologises for previous jibes by Foreign Secretary David Lammy.

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.

There are claims that Mr Trump has repeatedly told associates that Sir Keir is ‘very left-wing’.

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.’