In an expression of the kinder, gentler politics that has famously infused the Labour party in the past year, John McDonnell recently told a rally of Corbynistas that the Labour MPs trying to depose the leader are “fucking useless”. The vituperation is entirely mutual. The root cause of the party’s rolling crises is as easy to identify as a solution to its agony is hard to find. Labour has a leader who has totally lost the confidence of his colleagues in parliament. They fear that he is taking them on a trajectory that will end with the party’s worst election collapse since the 1930s. The MPs do not have the backing of a large chunk of the party selectorate that picks the leader. Much of that selectorate is wildly unrepresentative of the voters that Labour must persuade if the party is to survive as a plausible opposition, never mind become a viable competitor for power.

This is the Gordian knot that Labour MPs have been trying to unpick ever since Jeremy Corbyn became their unexpected and unwanted leader last September. One of their persistent errors has been to assume that he and those behind him play by the conventional rules of a parliamentary party. Many Labour MPs started off thinking that after decades as a backbench rebel, Mr Corbyn would make at least some effort to try to master the skills of leadership. Even when this was palpably not the case, they clung to a hope that there might be a peaceful way to broker a solution.

There has been much talk that the attempt to unseat Mr Corbyn was meticulously planned. The truth is that Labour MPs would not have acted this summer but for the Brexit vote. It was the shock of that, combined with collective horror about Mr Corbyn’s response to it, which finally pushed them into despairing action. When 65 frontbenchers resigned, they assumed he would realise that his game was up. They were wrong. He does not regard an inability to staff a parliamentary team as sufficient grounds to quit. In a ballot of Labour MPs, 172 of them declared that they had no confidence in the leader, with just 40 offering continued support. Every single living former leader urged him to recognise that this was unsustainable. Neil Kinnock has declared that he would have walked in those circumstances. Of course he would. Any previous leader of any of our parties would not have endeavoured to carry on when he had lost the support of his colleagues by a margin of more than four to one. But to think Mr Corbyn would resign in these circumstances was to mistake him for someone who thinks that parliament matters. “He could take us into the next election and lose 100 MPs and even then he wouldn’t think he had to go,” says one Labour parliamentarian.

One Labour MP who is usually a reliable interpreter of the party's mood thinks 'Owen has a massive mountain to climb'

So now they have reached the last resort. The leadership challenge has not been mounted in any great expectation that it will succeed. Labour MPs can see the essential ridiculousness of triggering a contest a year after the last one with the incumbent the favourite to win the leadership again. This is an act of utter despair by people who believe they have run out of any other options.

One of the great ironies about this is that no one looks happier than Mr Corbyn. When he launched his campaign last week, he looked more invigorated than at any time since he became Labour leader.

The prospect of spending the next nine weeks having to reapply for his position would have infuriated and depressed any other party leader I have known. Yet he declared himself to be “excited” by the prospect and I believe that. He now has a whole summer ahead of him when he doesn’t have to talk to his MPs or try to muster an effective opposition to the Tories. He can spend the summer doing what he most loves, which is communing with devotees who already agree with him rather than trying to engage with swing voters. He will travel from one Momentum rally to another Momentum rally telling his supporters that they are building a wonderful grassroots movement and in turn being hailed by his audiences as a hero. At his campaign launch, he was already suggesting what he’d do with the fruits of victory by talking about deselection of Labour MPs.

Do they have a chance of deposing him before the zealots in the constituencies start moving to unseat them? On the positive side for the challenge, it will be a binary choice between Mr Corbyn and Owen Smith, the Anyone But Corbyn candidate from the party’s soft left around whom MPs have coalesced. Angela Eagle had the guts to be the first to put her head above the parapet and displayed further quality of character when she stood aside for Mr Smith after he received more support from MPs. You could not have had a challenge in the name of “unity” with two “unity” candidates. At least the attempt to dislodge Mr Corbyn has avoided that absurdity.

Facebook Twitter Pinterest Owen Smith speaks at the first rally of his campaign for the Labour leadership at Friends’ Meeting House, Manchester last week. Photograph: Jack Taylor/Getty Images

The odds nevertheless look heavily stacked against the challenger. Members of Mr Smith’s team describe it as “tough, but doable”. They think that Mr Corbyn has lost support among long-standing members since last summer, but accept that he is probably ahead among those who have paid £25 to get a vote as a registered supporter. Quite a lot of MPs who are desperate for the challenge to succeed fear that it has come too soon. In their view, Labour activists needed to be given more time to come to their own conclusion that Mr Corbyn was leading them towards calamity. One MP expresses the anxiety of many that Mr Smith’s bid will run into a wall of “indignation” among party activists that Labour parliamentarians are trying to “bully” the membership. One of the challenger’s most formidable tasks is to prevent the Corbyn camp from defining this as a battle between “MPs” versus “Members”, “Westminster” versus “The People”. Some Labour MPs already sound reconciled to the attempt failing, but justify it on the grounds that “at least we can say to ourselves that we tried to do something”. One Labour MP who is usually a reliable interpreter of the mood of the party thinks “Owen has a massive mountain to climb”.

There was a small example of what the challenger is up against when he went to an event in Manchester on Friday and bumped into a woman wearing a T-shirt emblazoned with the slogan “I Voted Corbyn”. Rather to the consternation of members of his campaign team, Mr Smith devoted 20 fruitless minutes trying to win her over.

The core Corbynistas are not going to be shaken from their devotion to St Jeremy. If anything, the mutiny by MPs is only hardening their zeal. For them, it is heresy even to suggest that there might be some problems with what is happening to a party in which the atmosphere has become so poisoned that meetings of its local branches have been suspended because bullying and intimidation have become so rampant.

For Mr Smith to have a hope of winning, the constituency he must persuade are those you might call “soft Corbynistas”. That is why he is eschewing an ideological challenge to Corbynism – “I am just as radical as Jeremy”– and making his case on the grounds of competence.

There is certainly plenty of material for him to work with here. There is also perhaps a readier audience among at least some of the Labour membership to hear an argument about the importance of being a viable opposition. In today’s Observer, Neale Coleman, Mr Corbyn’s former head of policy, expresses his fear that the party is heading for a disastrous defeat under a leader who never showed any capacity when they worked together to go beyond sloganeering. Two former shadow ministers, neither of whom could be labelled as anything but leftwing, have explained their resignations by releasing anguished inside accounts of how their positions were made impossible by the Corbyn regime.

Thangam Debbonaire has described how she was appointed as a shadow culture minister without her knowledge while she was in the middle of cancer treatment and then unappointed, again without being told, when Mr Corbyn realised he’d given away part of someone else’s role. Lilian Greenwood, the former shadow transport secretary, concludes a detailed account of how she was undermined by saying: “Through my own personal direct experience I know that Jeremy operates in a way that means progress… is impossible. He is not a team player, let alone a team leader.”

Being a functional opposition matters to Labour MPs and to anyone else who hopes not to live in a perpetual Tory state. It matters to many Labour members too. The coming weeks will test whether it matters sufficiently to enough of the current Labour selectorate to do something about it.

The contest is already turning ugly. Still, some people will be happy. Mr Corbyn will enjoy himself wandering among the devoted. The media will have a juicy Labour civil war to report as a diversion from trying to explain the complexities of withdrawal from the EU. Just a pity about the country, which has never more needed an effective opposition and has never so lacked one.