Keir Starmer has gone from Clark Kent to Superman but faces his biggest test

Sir Keir Starmer has gone from politics’ answer to Clark Kent into a diplomatic Superman in less than a week but the Prime Minister may soon face the most agonising choices of his life.

It was all going so well. Sir Keir is not known for his dazzling charisma but he delivered a masterclass on how to charm a president when he arrived at the White House brandishing an invitation from King Charles for a second state visit.

Disaster struck the next day when Trump and had their Oval Office blow up on Friday but Sir Keir flew to the rescue. He hugged the Ukrainian president in Downing Street on Saturday and brought world leaders together in support of the imperilled nation on Sunday.

Even Conservatives have praised a PM whose premiership up to this point had been defined by debacles over freebies, infighting at Number 10, clashes with farmers and pensioners and despair concerning the economy. Now he is a bona fide international statesmen.

In an era when politics is dominated demagogues, autocrats and showmen, one of Sir Keir’s key selling points is that he is not nuts. His massive parliamentary majority means he will not be dislodged anytime soon – Britain, for so long rocked by Scottish independence efforts, wars and the culling of prime ministers, is now a beacon of stability.

The PM is desperate to secure a peace deal which is not a mere prelude to a further Russian invasion. He knows there is no prospect of Europe being able to replace American firepower in the near future so he is fighting to stop the United States abandoning to a miserable fate.

Sir Keir will hope Trump’s suspension of military aid is a negotiating tactic – a power play to force Zelensky into peace talks – rather than the final desertion of an embattled democracy.

Lord Mandelson, who is just weeks into his formal role as British ambassador to the US, will work night and day to stop the transatlantic alliance from collapsing. But the situation – in the words of Kemi Badenoch – is “profoundly worrying”.

The days when the US was locked in competition with Soviet Communism for influence in Europe are gone, and its commitment to the security and prosperity of its allies is also out of fashion, as demonstrated by Trump whacking NATO member Canada with sanctions.

Powerful figures in America’s foreign policy establishment view as a dangerous distraction when the US should be focused on containing China. The last thing Trump will do is make a multi-decade, Korean-style commitment to funnel troops and treasure into to police its border.

The grim story of this war is Ukrainian forces were given enough support to hold their positions but not enough to drive the Russians out – and that is not going to change.

Sir Keir may have to play the role of the friend who delivers bad news and tell Zelensky that the (US) cavalry really is not coming to the rescue, that a wildly imperfect deal is the best Trump will put on the table.

In such circumstances, the Prime Minister will have to decide what it means to stand with . Will the UK station thousands of servicemen and women in and throughout eastern Europe as it fights a new Cold War without the assurance of US protection?

If Zelensky and his generals refuse to give up the fight, will Britain support them in the devastating battles which await? UK voters are not upset to see foreign aid cash going to the defence budget – but will they tolerate cuts to welfare spending to deepen our involvement in ?

Without US support, what is the best outcome that Britain and the EU can deliver?

Sir Keir’s resolve and judgement will be tested like never before as this crisis unfolds. His decisions will shape the future of Europe.