DAN HODGES: Global threats are increasing. If Kamala loses the US election, Starmer may actually have to deal with them alone…

Sir Keir Starmer has decided to bet his whole house on Kamala Harris. Last week it was announced that the Prime Minister has dispatched his pollster Deborah Mattinson to the United States to assist the Democrats in their fight to defeat Donald Trump and retain control of the White House.

A Labour insider told Politico: “Democrats who follow British politics are fascinated by the speed with which Labour has come to power since the days of Corbyn. That has really caught people's attention.”

Donald Trump will also have taken notice of the idea. The former president, known for his thin skin, will not take kindly to one of his country's closest allies trying to thwart his renewed attempt to make America great again. However, a Labour source noted wryly: “If Mattinson really wants to help Kamala Harris, she will have to do more than show her how to get the 34 per cent of the vote that Labour got here.”

Kamala Harris waves to the crowd after her speech on the final night of the Democratic National Convention in Chicago last month

So far, the official line from Downing Street has been that they would be happy to work with whoever is elected in November.

But privately, fears of a Trump victory and the consequences for the fabled “special relationship” between Britain and the USA are growing. There is even talk in the government of making relations “Trump-proof”. David Lammy is leading the effort to open channels between Downing Street and a possible MAGA government.

Given that Lammy once called Trump a “woman-hating, neo-Nazi-sympathetic sociopath” – a remark Trump’s son Eric dismissed last month as “stupid nonsense” – this does not seem like the easiest diplomatic mission for our new Secretary of State.

But allies say he has made some progress, not least in the form of a surprising friendship with Trump's vice presidential candidate, JD Vance.

“They have met several times and built a strong bond,” a State Department official told me.

“They realized there were a lot of parallels in their backgrounds. They both grew up in poverty, in the midst of broken homes. They talked about it a lot. David now considers JD a friend.”

But the reality is that despite this growing bromance, the gap between Prime Minister Starmer and President Trump is likely to be so wide as to be almost unbridgeable, which in turn could leave Britain and its new Labour government in a worrying state of isolation.

Last week, Starmer and Lammy announced they would impose an arms embargo on Israel. Although the Prime Minister insisted the decision had been made on the basis of legal advice, the level of outrage in Jerusalem was unprecedented.

The Israeli government publicly condemned the decision, calling it “shameful.” Israeli opposition leader Yair Lapid claimed that the ban actually undermined the position of moderate forces in the country who were pushing for a ceasefire. “Friends and allies should stand together in the fight against terrorism,” he rebuked.

There were even reports that the arms embargo had angered the Biden administration, although government sources insisted that US officials “respected the decision.”

But an important strategic alliance has been undermined – and at present Britain has very few of them to rely on.

In the first months of his term in office, Starmer and his team have sought to “reset” relations with the European Union – and claim to have made some progress in doing so, pointing to the “E3” axis currently being built with French President Emmanuel Macron and German Chancellor Olaf Scholz, as well as Lammy's recent joint diplomatic visit to the Middle East with French Foreign Minister Stephane Sejourne.

Prime Minister Sir Keir Starmer, who sent his pollster Deborah Mattinson to the US to support the Democrats in their fight against Donald Trump.

“The Sunak government spent five months getting the mission with the French sorted,” one minister told me, “and we did it in a matter of weeks.”

But as the British newspaper The Mail on Sunday reports today, progress towards a new, comprehensive agreement with the EU, which Starmer actually wanted to present in January, is making little progress.

British Foreign Office officials point out that this is partly due to the time it will take to form a new EU Commission. But as one minister candidly admitted, the politics of Brexit mean there is limited scope for renegotiating relations with Europe.

“Keir has made it clear he doesn't want to reopen that can of worms,” ​​he told me. “We're not going to rejoin. We're not going to join the single market or a customs union. Free movement is off the table. So there are limits to how far we can go.”

This is the realpolitik of Starmerism. One Labour insider told me: “He has painted himself into a corner. He doesn't want to re-open Brexit, so he can't offer Europe anything meaningful.”

Meanwhile, global threats are increasing. Britain is currently locked in a hot war with Russia, backed by Ukraine. The cold war with China is getting colder as cyber agents target British hospitals, power plants and even the royal family. Iran is threatening a new wave of Western terror while continuing its non-civilian uranium enrichment program.

It is becoming increasingly likely that our new Prime Minister will be forced to confront these threats alone.

When Tony Blair came to power in 1997, he was welcomed into a new global progressive alliance.

Bill Clinton occupied the White House. In Germany, the Social Democrats under Gerhard Schröder were close to taking power. In France, the Socialists under Lionel Jospin began the phase of “cohabitation” with Jacques Chirac.

The political landscape facing Starmer could hardly be more inhospitable. In France, Marine Le Pen is still hot on Macron's heels. In Germany, the far-right AfD is on the rise. Italy's Giorgia Meloni and Hungary's Victor Orban are thriving as Europe's rabble-rousing troublemakers. And his natural allies in the European Commission see him as a sympathetic irrelevance.

So in some ways, his gamble with Kamala Harris is logical. A Democratic victory would put a stop to the growing wave of populism – not to mention a rebuff for Trump's biggest supporter, the MP for Clacton.

And it would also help protect the diplomatic architecture of NATO and the G7. That is why Starmer is flying back to Washington on Wednesday.

If Kamala Harris were to lose on November 5, Britain would indeed be left alone. Currently, polls show the race to be on a knife edge, even if her predicted post-convention surge has failed to materialize.

So Sir Keir should hope that Deborah Mattinson can work her magic in the coming weeks and months, because if she doesn't, the bromance between David Lammy and JD Vance could be the Grand Atlantic Alliance's last hope.