After the debates on Syria and antisemitism, Labour is now two parties – and the split could be coming soon

Team Corbyn certainly frets about a centre party. Not because it would do a Macron and sweep the board, but because the breakaway SDP helped Margaret Thatcher win thumping majorities

Labour is two parties now. The pretence that Jeremy Corbyn and his centrist MPs belong in the same one has been shattered by recent events. While the spotlight was on domestic policy and Brexit, Labour’s two tribes just about held it together. Some Corbynsceptics even acknowledged they had got him wrong after his brilliant performance at the general election, called a year ago today.

The truce was always fragile. It ended last month after Sergei Skripal and his daughter were poisoned by a nerve agent at Skripal’s Salisbury home. Corbyn’s refusal to unequivocally blame Russia highlighted his foreign policy, exposing the gulf with some Labour MPs. Then further evidence of antisemitism in the Labour Party reminded his critics that, while no one accuses him of holding such views, he has been slow to tackle it.

The chemical weapons attack in Douma, Syria, shifted the spotlight to foreign intervention. Corbyn was in tune with public opinion in opposing the air strikes by the United States, France and Britain. The long shadow cast by Iraq works in his favour. But a sizeable number of Labour MPs, including some who regret voting against air strikes in 2013 because the West missed a chance to topple Bashar al-Assad, viewed Corbyn’s call for United Nations approval as his latest excuse for inaction because he knew full well that Russia would wield its veto.

Corbyn tried to unite his party by staging an emergency debate on the need for a War Powers Act rather than on last weekend’s bombing. But during two days of Commons discussion, his centrist critics turned their fire to Corbyn’s non-interventionist policy and 52 abstained in protest at the end of Tuesday’s debate.

Then Labour’s deep divisions were displayed again in a Commons debate on antisemitism, with Labour MPs Luciana Berger and Ruth Smeeth giving harrowing stories about the terrible abuse they have suffered. Corbyn can’t be held responsible for every tweet by overzealous acolytes who do not act in his name, but he was warned about the problem two years ago and has shown a failure of leadership in not tackling it.

The problem is that the things that have been said over the past two days cannot be unsaid. The mood inside the Parliamentary Labour Party has changed. “There is no longer any pretence,” said one MP critic. “The level of despair is back to mid-2016” (when 80 per cent of Labour MPs declared they had no confidence in Corbyn).

Where does it go? There won’t be another kamikaze leadership challenge; Corbyn retains the support of the overwhelming majority of Labour’s 550,000 members. But some of his MPs believe his approach to security matters makes him unfit to be prime minister, and so it’s no surprise that chatter about a breakaway centre party has revived. There is undoubtedly a gap in the market: Corbyn would head the most left-wing government in the country’s history, while the scandalous treatment of the Windrush generation migrants from the Caribbean remind us of the Conservative Party’s nasty side under its present leader.

I suspect that opinion polls will show a potential opening for a new force.

But filling the gap will be hellishly difficult under our archaic first-past-the-post system, which the Tories and Labour keep on life support out of self-interest. Ukip’s rise was fuelled by the proportional system used in European Parliament elections.

A new party would need a lot more than the £50m put aside by businessman Simon Franks. It would take a sizeable number of Labour MPs to have credibility. The Liberal Democrats, less tribal under Sir Vince Cable, would probably merge into it. It would also need a leader – a British Emmanuel Macron.

Team Corbyn certainly frets about a centre party. Not because it would do a Macron and sweep the board, but because the breakaway SDP helped Margaret Thatcher win thumping majorities in 1983 and 1987 by splitting the centre-left vote. There are still things Corbyn can do to prevent the unofficial split becoming formal and hold his party together. He should make it clear to his grassroots followers that MPs who have spoken out on antisemitism should not be deselected. He should abandon plans to make it easier for local parties to sack MPs through trigger ballots.

Corbyn has one last chance to get a grip on antisemitism with the arrival of Jennie Formby as Labour’s general secretary and his meetings with Jewish leaders next week. He should ensure tough disciplinary action against those found guilty, which will mean upsetting old friends and there being no way back for Ken Livingstone.

I doubt we’ll see a new centre party soon. There are some Labour figures who think that the parliamentary votes on the Brexit deal will provide an outside chance of a realignment involving pro-European Labour, Lib Dems and even a few Tory MPs. Don’t hold your breath on that one.

There is no guarantee anything will happen at all. Breaking up is hard to do. Corbyn critics may play a waiting game, until the battle for the soul of the party that would break out if it doesn’t win the next election.

But the chances of a breakaway have increased in the six weeks since Salisbury. As another Labour MP put it: “We can’t go on like this. We’ve been sticking together for the sake of the kids. Now they’re going off to uni and we’ve got to decide what to do.”