Something is going on in the Labour Party and it isn’t on the moderate wing of the party. We are sat back feeling slightly bemused and trying to understand manoeuvrings that are going on deep within the left of the party. It’s correct for us not to interfere or undermine Jeremy Corbyn as this would merely cause his supporters to rally round him.

Something has snapped in terms of the relationship between large sections of his former support and Corbyn. This could be down to a sustained run of double-digit Tory opinion poll leads, or it could be down to the divergence between Corbyn and the older anti-European Bennite wing of the left and younger more pro-immigration, pro-European activists brought to a head by the whipped vote on article 50.

Overlaying this growing schism over whether Corbyn needs to step aside is a split in his own office over whether Diane Abbott’s abstention due to “sickness” on article 50 was acceptable given that other shadow cabinet members had to resign because they disagreed with the three-line whip he imposed; and the split in Momentum between supporters of Jon Lansman’s control of the organisation and backers of a traditional grassroots-controlled delegate structure more open to control by smaller factions, including Trotskyist ones.

Lots of people are on manoeuvres. Owen Jones has finally given full voice to the critique of Corbyn he has long been hinting at. Even Derek Hatton has forsaken the leader. And there is an array of alternative leaders either being ramped up or ramping themselves up: Emily Thornberrry, John McDonnell, Rebecca Long-Bailey, Clive Lewis, Angela Rayner, Lisa Nandy.

Labour’s moderates need to beware hard left wolves in soft left sheep’s clothing.

Some of the people named above genuinely don’t share Corbyn’s politics, but come from a positioning a little to the left of Ed Miliband. Their election would reunite the party and make it a happier place to be an activist in the short term, but an inevitable consequence of a leader positioned a little to the left of Ed Miliband would be a general election result a little bit worse than in 2015, another five years in opposition wasted, another five years of the Tories in power trashing public services and the welfare state, and we would be back at square one in 2020, with the Hard Left again saying “look you can’t win either”.

Others of those named remain organisationally wedded to the Hard Left even if they are presenting a softer public image. Replacing Corbyn with someone a bit more competent, a bit more charismatic and a bit more prepared to compromise would have a nugatory impact on Labour’s electoral performance. We might limit our losses to tens of MPs rather than dozens. But the party will still be fundamentally messed up if it has a leader whose allies on the national executive committee (NEC) and in CLPs are from Momentum and who supports Momentum candidates in internal party elections and selections.

There may really be an equivalent going on of the 1985 realignment of the left, when the soft left Labour Co-ordinating Committee and Tribune Group of MPs broke away from the Bennite hard left to back Kinnock’s leadership.

But at the same time there may be people whose hearts remain on the hard left but are re-positioning themselves for careerist reasons to try to avoid being taken down with Corbyn’s leadership when it crash lands.

A good acid test of which people are really coming to their senses and are on a political journey towards an electable Labour Party and which ones are playing cynical political games is who they endorse in this year’s internal political elections. If they publicly back the moderate candidates for the Conference Arrangements Committee and National Constitutional Committee it is a good sign that they are serious about what Labour needs to do to recover. If they continue to back the Momentum candidates we know they are not serious at all, and we know that if someone who does that becomes leader they will appoint hard left members to the NEC and key shadow cabinet posts and make Labour’s unity, let’s alone it’s recovery, impossible.

The Parliamentary Labour Party doesn’t have to settle for some kind of Corbyn-lite new leader. The PLP tried triangulating Momentum with Owen Smith in 2016 and it did not work.

Unless the rules are changed by an annual conference, all candidates in a leadership election when there is a vacancy require 15 per cent of MPs to nominate them to get on the ballot paper.

In the event that there is a vacancy the PLP should veto any candidates who represent Momentum with a smiling face or a bit more competence. Ideally they should also skip anyone who would just replay the 2010-2015 experience and go straight to someone who could have a transformative impact on the party’s reputation with voters who last voted Labour in 2005 (and younger voters with the same characteristics) and win people straight back from the Tories, UKIP and SNP.

Even if a left candidate does get on the ballot it is lazy to assume they would start as the favourite, because the composition of the party electorate will dramatically change. Thousands of 2015 and 2016 joiners who voted for Corbyn twice are already quitting, disillusioned because they have belatedly discovered he is a lifelong anti-European. Tens or hundreds of thousands may quit if the leader who inspired them to join steps down. And a prime criterion for any moderate candidate is that they can do what Corbyn did in reverse and inspire hundreds of thousands of people to become registered supporters to save the Labour Party.

Any new leader needs to not just address the public’s current concerns about Corbyn relating to competence, charisma, foreign policy and national security, they also need to address the public’s 2015 concerns about Labour’s economic strategy, our stance on immigration, and whether we had a strong enough leader.

Otherwise we won’t be resurrecting Labour as a party of government; we will just be slowing down our decline into marginality and irrelevance.

As in all the most successful periods of Labour’s history, a broad united leadership spanning the moderate, centre and soft left of the party, and even people further left than that who are talented and prepared to be team players – needs to be constructed. But it doesn’t follow that the leader of this coalition needs to come from the soft left – that risks not being a dramatic enough change to convince the public that Labour has really learned the lessons not just of the last two years but of the five that preceded it.