In politics, it is not your enemies who are the death of you. The game is up when you lose those you once called friends. The curtain finally came down on Theresa May when previously loyal Tory MPs declared that it was time for her to book a removal van. The most alarming development since the European elections for Jeremy Corbyn is not the sound of Tom Watson and other familiar foes challenging him. It is the anger of those whom he once counted as allies.

Jeremy Corbyn won’t listen to the many and heeds only the few Read more

The catalyst for a week of recriminations was Labour winning just 14% of the vote, the worst performance in a nationwide election since 1910 when the party was still in its infancy. This was a bit better than the more catastrophic result for the Tories, but emotionally it has been more of a shock to Labour because at least the Conservatives had warning that they were going to be obliterated. In its former stronghold of Scotland, Labour came in fifth with a vote share in single figures. In Wales, another historic bastion, it was third. Even in London, the spiritual heart of Corbynism, the party was drubbed into second place by the Lib Dems.

The immediate effect has been to move the balance of argument in favour of those who are pressing for Labour to become a party unequivocally opposed to Brexit. If there were any doubt before, there can be no question now that trying to face two ways on the most important issue facing Britain has alienated millions of voters on both sides of the great and defining question. It is true that Labour, which has MPs representing some of the most pro-Remain and some of the most pro-Leave areas of the country, has always faced a genuine strategic dilemma. It is also clear that equivocation is not a solution to that dilemma when voters are rewarding parties with a clear position and punishing those that try to hide in a thicket of obfuscation. “Constructive ambiguity” has become destructive of Labour’s chances of forming the next government.

Yet Mr Corbyn has responded to this dramatic challenge not by coming off the fence but by wobbling about on it. Since the Euros, he has sometimes sounded a bit warmer towards another referendum, remarking at one point that “we are ready to support a public vote on any deal”. Then, in the way that we have come to expect from him, he followed zig with zag and said any decision “is some way off”. He is still refusing to move to the position that Remainers in his own party and beyond are demanding. He is not making a definite promise of a fresh referendum, no ifs, no buts, no hesitations, deviations, equivocations and qualifications, and no sending out Barry Gardiner to baffle everyone comatose. The Labour leader will still not commit to campaigning to stay within the EU, the position the vast majority of the party’s members want him to adopt. Polling suggests that more than 40% of those members voted for a different party at the Euros and another tenth went on strike by staying at home.

Facebook Twitter Pinterest Emily Thornberry: a loyalist who was one of the first to respond to the Euro elections by blaming the cataclysm on the party’s lack of clarity on Brexit. Photograph: Sophie Hogan/PA

Instead of reflecting on what this says about them and their broken strategy, the response of Team Corbyn was to expel one of those mutinous members, a Mr Alastair Campbell, for revealing that he had voted Lib Dem for the first time in his life. It is still not entirely clear exactly who decided to boot out Tony Blair’s former director of communications, a man who has put in many more years as a Labour member than some of Mr Corbyn’s closest advisers. It is implausible that this could have happened without the assent of the Labour leader and his coterie, and highly likely that it was done at their instigation. Perhaps they calculated that throwing out Mr Campbell would distract the media and be popular with the party’s grassroots. The Corbynista base would surely cheer the eviction of a prominent player in the New Labour years who is closely associated with the Iraq war. They instead achieved the unexpected feat of making Mr Campbell a martyr to a popular cause. A variety of other Labour names, including the former home secretary Charles Clarke and the former Speaker Betty Boothroyd, reacted by making “I am Spartacus”-style declarations that they also voted for other parties in the Euros. A lot of Labour members have taken to social media to do likewise and dare Mr Corbyn to #ExpelMeToo.

The expulsion coincided with confirmation from the Equality and Human Rights Commission that it was launching a formal inquiry into anti-Jewish racism within the Labour party. This invited everyone to contrast the alacrity with which Mr Corbyn’s thought police purged Mr Campbell with the sluggish response to cases of antisemitic abuse.

The former New Labour spinmeister could never be confused with a Corbynite. And other critics are also old foes who have been emboldened by his current weakness. More unnerving for the Labour leader is the behaviour of people he previously counted as allies. Emily Thornberry has been a loyalist, and often a combative one, since he made her shadow foreign secretary, but she was one of the first to respond to the Euro elections by blaming the cataclysm on the party’s lack of clarity on Brexit.

Her mind will have been concentrated by the Lib Dems topping the poll in Islington, the north London borough that both she and Mr Corbyn represent in parliament. She is also interested in having his job when he decides to spend more time with his marrows. Diane Abbott, the shadow home secretary, is the Labour leader’s oldest friend in the shadow cabinet. Even she has been aligning with his critics, tweeting: “When we come in third after the Brexit party, that is a clue something is wrong with our strategy. We need to listen to our members and take a clearer line on a public vote.”

I may have remarked before that the Labour leader’s endless weaving and swerving over Brexit has done deep damage to his core brand by revealing him as just another of the cynical, unprincipled, fork-tongued, opportunistic hack politicians that he has always professed to despise. It is some achievement to have a personal approval rating worse than that of Theresa May, a prime minister who has just been forced to quit. Erstwhile worshippers at the shrine of Saint Jeremy are losing their religion. “I despair,” one wrote last week.

Disillusionment is eating into the very heart of his internal support. Laura Parker, a leading light of Momentum and one of Labour’s disappointed candidates in the Euro elections, voiced her discontent: “We can’t fudge our way out of the Brexit mess”.

Facebook Twitter Pinterest ‘The most intriguing figure in this struggle is John McDonnell.’ Photograph: Andy Rain/EPA

The most intriguing figure in this struggle is John McDonnell. When he and Mr Corbyn captured Labour’s commanding heights four years ago, the shadow chancellor took the view that they needed to stick closely together and never display any differences when they had so many hostile forces arrayed against them. Even between them there is now visible daylight. Mr Corbyn’s circle have always regarded the People’s Vote campaign, in which Alastair Campbell plays an influential role, with deep suspicion. Mr McDonnell, by contrast, has had cordial dealings with those pressing for another referendum. I doubt that the shadow chancellor feels that passionately one way or another about Brexit. But he is extremely interested in power.

This doesn’t amount to an incipient “coup” against the leader; that is a product of paranoid imaginations. Labour MPs have not forgotten that the attempt to dislodge him in 2016 was a hopeless failure that only made him stronger. Fury is instead being targeted at his inner circle. Since the king himself cannot be openly accused of wickedness, the blame must fall on his senior courtiers. David Blunkett, the former Labour home secretary, tells us today that Seumas Milne, the director of strategy, and Karie Murphy, the leader’s chief of staff, “must surely be held to account”. He is speaking for the members of the shadow cabinet who believe Mr Corbyn is “the prisoner” of his two most senior aides and that removing them is the key to moving him on Brexit.

That’s easier demanded than done. They aren’t going to gladly purge themselves and he won’t want to do it. Surrendering their scalps would be popular with many of the shadow cabinet, but it would also be read as a sign of extreme vulnerability. It is also moot whether Mr Corbyn could personally function deprived of Mr Milne and Ms Murphy. When enemies are growing bolder and erstwhile allies are deserting, the instinct of the besieged leader is to clutch tight to the few he still counts as friends.

• Andrew Rawnsley is Chief Political Commentator of the Observer