Five days after Brexit, the impact of the UK’s vote to leave the EU is becoming clearer. Nowhere is that impact being felt more keenly than at the top of the country’s major political parties. The Prime Minister, David Cameron, has quit – declining to trigger the Article 50 negotiations on EU exit, stating that this would be a decision for his successor, and reportedly saying to aides in Number 10, “why should I have to do the hard shit?” For a move being hailed in some quarters as a scheming act of political calculation deserving of a sub-plot on Game of Thrones, it looks remarkably like a surly table-flip from a man who had just lost a very foolish bet. The Conservative party finds itself in disarray. People like George Osbourne and Boris Johnson, whose support for Leave was entirely designed to undermine Cameron and vacate the Prime Minister’s job for himself, have recognised the the land-mine that Cameron chucked underneath the chair as he departed and are backing rapidly away from the top job. Meanwhile, political lightweights barely deserving of the term “mediocrity”, like fatuous NHS hatchet-man Jeremy Hunt, witlessly toss their hats into the ring.

While the Tories were fractured throughout the campaign and now find themselves split more deeply than ever before, Labour backed the Remain campaign with fairly solid party unity. My former MP, serial dissenter Kate Hoey, was one of only a handful of Labour MPs to rebel and support Leave; 99.2% of Labour MPs supported Remain. Given the anger, fear and upset over the Leave vote, the disorganisation of the leaderless and rudderless Conservatives, and the potential for striking strong alliances with strongly pro-remain local parties in Scotland and Northern Ireland, you’d think that Labour would be out there making plenty of hay in the bright sunshine, wouldn’t you?

Well, you’d think that. Instead, most of Labour’s Shadow Cabinet has resigned, and a vote of no confidence in the party’s leader, Jeremy Corbyn, has been passed by a huge margin. 172 MPs voted no confidence, to 40 who supported Corbyn (13 abstained, and 4 MPs spoiled their ballots, which I hope was a slightly pointless protest and not an indication that Labour has four elected MPs who don’t know how ballot papers work). Corbyn says he won’t resign. There’ll probably be a leadership challenge. Just as the Conservatives find themselves in crisis, Labour has found a way to sink into an even deeper crisis.

Of course they have. We’re talking about Labour, a party riven right down the middle by a deeper divide than Tory Euroskeptics could ever create; the divide between the shiny-faced, PR-groomed New Labour generation, and the frumpy, stubborn and sincere old socialists. The former group are career politicians who, though often possessed of fine qualities and beliefs, fundamentally pursue little other than re-election, and believe fervently in the pursuit of politics through opinion polling, focus groups and post-modern campaign methods. The latter are generally drawn from activist or trade union backgrounds and see their socialist beliefs as a hill worth dying on; hardened by Labour’s years in the electoral wilderness in the 80s and 90s, they regard electoral failure as a price worth paying for staying true to their principles.

Right now, one of the old socialists is in charge of the Labour party for the first time in a generation. Corbyn was voted in by a huge margin by a combination of long-term rank-and-file Labour members and a wave of newcomers shocked by the Conservatives’ 2015 election victory and enthused by Corbyn’s sincere, unpolished approach. The party loves Corbyn – polls of Labour members suggest he’s actually grown in popularity since his landslide election. Labour MPs, on the other hand, hate him. They’re mostly drawn from the ranks of New Labour and remain starry-eyed over the success of the Blair era, thus innately suspicious of the resurrected spectre of 80s and 90s Old Labour – but even among those who aren’t, their immediate concerns and motivations are simple; they want to keep their jobs. They want to be re-elected. To the MPs who make up the Parliamentary Labour Party (PLP), the principles and policies of the Labour leadership play second fiddle to the leadership’s ability to retain its seats in parliament.

Ever since Corbyn took the helm of the Labour party, he’s struggled to maintain control of the PLP. Some MPs are loyal to him because they genuinely believe in him and his principles. Others are loyal because they respect the position of leader and the decision of the party members. On the other side, some are intrinsically, vehemently opposed to him because they disagree with his principles and positions. In the middle rests the majority of the PLP – who fear that Corbyn can’t win an election, but were willing to hold their peace and give him a shot at the leadership, since the next election wasn’t scheduled until 2020.

It’s now extremely unlikely that the next election will be in 2020. Brexit has upended all political calculations. By far the most likely outcome is a general election before the end of this year. The new Conservative leader will not only face an impossible decision regarding the EU exit trigger, he or she will also be seen to lack a mandate to govern. That will be even more the case if, as is likely, it’s one of the party’s rather less impressive specimens at the helm, with “big beasts” like Boris Johnson, George Osbourne and Theresa May keeping their distance from the poisoned chalice.

When Jeremy Corbyn took over Labour and the centrist / right-leaning sides of the party and the media brayed with horror about his consigning the party to electoral purgatory, I argued that Corbyn’s job was not, for now, to win elections. With five years to the next election, his job was to move the Overton Window of Britain’s political conversation; to shift the range of “acceptable” policies and positions, which has drifted inexorably rightwards since the late 1970s, back towards the centre-left. He needed to make it possible to discuss economic inequality, workers’ rights, trade unions, the social compact and redistributive justice without being automatically labelled a “loony leftie” – so a leader, himself or another, championing those things in 2020 could actually stand to win an election. The only way to do that is to keep discussing those things, to be called a “loony leftie” and far worse so many times that the words lose their meaning and your views start to become not crazy, or wild-eyed, but a regular part of political discourse.

That approach takes time. Labour has run out of time. An election in 2016 could, some argue, see Labour wiped out in northern seats that voted strongly to leave the EU. Even with the Tories crisis-struck and infighting, Labour hasn’t had the time or opportunity required to shunt the national debate to the left; Labour MPs fear for their seats even in the most favourable electoral climate for them in a generation. So they want Corbyn gone; they want someone more traditionally “electable”, more slick in presentation, more willing to listen to focus groups and do what’s needed to win an election today, not to change a national conversation in five years’ time.

They’re not wrong. I believe that Britain’s political debate has been utterly poisoned by a shift to the right that has made voices of fascism and authoritarianism more valid and credible than voices calling for centre-leftist redistribution and justice. I believe that the only way Labour reclaims its heartland districts and the trust of the British working classes is by re-embracing social democracy and being willing to grit its teeth and champion unpopular things like trade unions and workers’ rights, fighting through the scorn until they’re re-established as a pillar of British society. I believe that a leader like Corbyn, for all his failings, could play a vital role in that slow, difficult and necessary process.

I also believe in political realities, though, and the political reality is that Corbyn lacks authority within his own party and has yet to make significant headway on making his arguments sound valid to the electorate. Those plotting against Corbyn are despicable opportunists in many regards, but even while finding their nakedly careerist ambitions contemptible (Hilary Benn, a profoundly unimpressive politician who owes his entire career to the fact that his father was Labour stalwart Tony Benn, is a particularly egregious example) it’s hard to deny that they have a point. Labour going into a 2016 election under Corbyn poses a profound risk not only to the Labour Party and their seats, but to the people they are meant to represent.

Consider; whatever Conservative party emerges from its current mess will almost certainly be more right-wing and illiberal than its current incarnation. It’s unlikely to win many extra seats in the election – it’s more likely to slide backwards, and Labour may even win some seats from them. However, emboldened by Brexit, the even more aggressively far-right UKIP could win several seats, granting the far-right party more MPs from traditional Labour heartlands. The Tories, losing their slim majority, would face another coalition – either with their old partners, the Liberal Democrats, whom Cameron used effectively to hold back the right-wingers in his own party during the last coalition government, or with UKIP. With the right wing in control of the Conservative party, unleashed by Brexit and Cameron’s resignation, they’re unlikely to countenance another coalition with the Lib Dems; a nightmare coalition of a right-leaning Conservative party, the borderline fascist UKIP and the Ulster Unionists seems perhaps the most likely outcome of a Labour stumble in the 2016 General Election.

That would spell catastrophe for the UK as a whole, but even more so for the British working classes whom Labour is tasked, often thanklessly, to represent. The further austerity and erosion of rights for workers, tenants and consumers that would result would be nothing short of obscene; the damage to Britain’s hard-won and fragile social cohesion between diverse ethnic groups would be absolute, and absolutely heart-breaking.

Corbyn was the right leader for Labour when the task was to drag the party, and then the British people, back to firm centre-left ground – when stubbornness and a willingness to shrug off unpopularity were the key requirements for the role. Corbyn hasn’t changed, but the job has. The job now is to mitigate the damage of Brexit and to avoid plunging Britain into an even deeper crisis at the likely impending election. Corbyn isn’t the man for that job. While the disloyalty and scheming of those who have plotted against him from the outset should never be forgotten (we can hope that several of them will be de-selected by their local parties in retribution), many of the 172 who voted against him this week have done so out of genuine fear not just for their own jobs but for the future of the UK. Corbyn is the right man, but this is the wrong time.

Sadly, the very stubbornness that made him perfect for the job of changing the Labour party is now preventing him from doing the decent thing and stepping down. Labour’s best hope is a quick challenge, a decent new leader (Angela Eagle wouldn’t be a bad choice, all things considered) and a rapid healing process allowing them to get this behind them before the Conservatives get their house sufficiently in order to consider a general election. The Corbyn “project” will have to be paused – but the alternative is so very much worse.