Labour is gearing itself up to oust Corbyn - but other candidates for leadership aren't who you might expect

Triggering a leadership contest would require the backing of only 51 MPs and MEPs

During the Labour leadership contest Jeremy Corbyn said he was open-minded about voting reform and suggested the system used in Scotland might be extended to Westminster (Reuters)

Something has changed inside the Labour Party during the bitter row over antisemitism. A few weeks ago, if a group of Labour MPs with no love for Jeremy Corbyn were chatting, they would have discussed whether he would lead the party at the 2020 general election. Today the same group would discuss when Corbyn will be forced out before then.

“The tectonic plates have shifted,” said one Labour frontbencher. “The widespread view across the PLP [Parliamentary Labour Party] now is that he is not going to last the course.” Corbyn’s delayed response to the allegations of antisemitism will not in itself provoke an attempted coup. What the controversy did was to crystallise a feeling among many Labour MPs – fewer than 20 out of 232 voted for Corbyn last year – that he is not up to the job and must go.

It is wrong to say that the claims are being invented by his internal enemies to pave the way for a leadership contest. The person who did most to fan the flames was Ken Livingstone, a friend of Corbyn. The critics of Corbyn’s handling of the affair are not all “embittered Blairites”, as Livingstone argued, but included his closest ally John McDonnell, the shadow Chancellor.

Triggering a leadership contest would require the backing of only 51 MPs and MEPs. Although the critics have the numbers, it is far from certain they will deploy them.

The antisemitism row has made a challenge more likely, and given the rebels a cause. However, they know they have only one shot before 2020 and they are not even close to rallying behind a single plan or alternative candidate. “There are eight different plots; we need one that will work,” said one Shadow Cabinet member.

Some Blairites believe their best bet is to endorse a “soft left” figure, probably one serving on Corbyn’s frontbench rather than a backbench refusenik, to boost the chances of the party uniting behind him or her. Angela Eagle, the shadow Business Secretary, is the most likely to fit that bill.

Lisa Nandy, the shadow Energy Secretary, also has her admirers. So does Hilary Benn, the shadow Foreign Secretary, but he is reluctant to put himself forward for the top job, and his support for bombing Isis in Syria alienated many party members. If the anti-Corbyn forces coalesce behind a new face, it could be Dan Jarvis, a former soldier now on leadership manoeuvres, but who some colleagues say is not yet ready for action.

Despite brave talk about a coup, Corbyn still enjoys the overwhelming support of the Labour members who will decide the leadership and who gave him a huge 59 per cent mandate only eight months ago. A YouGov survey suggests that he would now win 43 per cent of first preference votes, and 62 per cent after second and third references were reallocated. Yet some MPs insist the grassroots mood is changing, that some members who voted for Corbyn last year now regret it– not because of his left-wing views, but because of a lack of competence, of which the antisemitism row is a good example.

A leadership challenge would not be launched until after the 23rd June EU referendum, since moving more quickly would divert Labour’s energies from the Remain campaign. A key factor in whether Corbyn’s critics press ahead will be Labour’s performance in Thursday’s elections to English councils, the Scottish Parliament and Welsh Assembly, and for Mayor of London.

Corbyn’s enemies have deliberately set the bar high, saying the Opposition should win 400 council seats at this stage of the electoral cycle. Independent experts predict that Labour could lose more than 100 seats because the party did well when the seats up for grabs were last contested. This week Corbyn refused to play the expectations game but naively gave a hostage to fortune by saying: “We’re not going to lose seats.” His spokesman said afterwards that Corbyn didn’t mean it.

Any coup would need the tacit support of Tom Watson, the deputy leader, and Rosie Winterton, the chief whip. The first phase could be a wave of resignations by several Shadow Cabinet members, who would warn that Corbyn was leading the party to electoral disaster in 2020.

The anti-Corbyn mood is now black enough for such hurdles to be cleared. But the fear stalking the plotters is that, even if they prise Corbyn out, another left-winger could win the ensuing leadership election. The most likely candidate would be McDonnell, who has dismissed as “ludicrous nonsense” growing speculation about a faultline between him and Corbyn, but would probably run if Corbyn stood down or was forced out.

Corbyn said on Tuesday he is “enjoying” being leader but does not look like a man who is; some critics believe he might just walk away and try to hand over the baton to another left-winger. McDonnell might enjoy less grassroots support than Corbyn, yet it might still be enough to see off a challenger.

Corbyn’s critics are not playing a clever hand. By advertising their plotting, they may help Team Corbyn blame poor election results on the MPs refusing to accept his mandate, deflecting criticism from his own performance. Indeed, the “blame game” has already begun in Labour circles. For Labour from now on, things can only get bitter.