Corbyn's new party - is it happening and could it damage Labour?

High profile left winger Zarah Sultana has quit Labour and vowed to launch a new political party with Jeremy Corbyn.

That, however, seems to have come as news to him.

In a social media post, the former Labour leader congratulated Sultana on her "principled decision" to leave and said he was "delighted that she will help us build a real alternative".

But he said "the democratic foundations of a new kind of political party" were still taking shape and discussions were "ongoing".

Sultana appears to have jumped the gun, taking not just Corbyn but others involved in the project by surprise.

But that does not mean it is not happening.

There is no name yet - Arise and The Collective have been bandied about. Corbyn is thought to like the phrase "Real Change", but not necessarily as a party name.

No timetable for a launch has been agreed, although there has been talk of fielding candidates at next May's local elections.

But all of those involved in the project believe there is a huge gap in the market to the left of Sir Keir Starmer's Labour Party, with millions of potential votes up for grabs.

Are they right?

And what would the arrival of a new socialist party mean for the Greens who have scooped up many left-wing voters in recent times - not to mention the Labour Party itself?

It is very difficult to assess support for a party that does not yet exist, has no leader and no policies.

Pollsters More In Common recently tested the sort of support a party to the left of Labour would have – specifically one led by Jeremy Corbyn.

Their research suggested it could pick up 10% of the vote - reducing Labour's standing by three points but far more dramatically eating in to support for the Greens, which would fall from 9% to 5% in the polls.

Notably, a Corbyn-led party could become the country's most popular party among 18- to 24-year-olds with 32% of the vote.

Former Corbyn aide Andrew Murray said Sir Keir Starmer had "created the space" for a party to Labour's left by ruthlessly expelling left wingers from the party and dropping his leadership campaign promises.

Speaking to GB News's Choppers Podcast, Murray said Labour's 2017 vote - 3.2 million more than Sir Keir's in 2024 - showed the scale of potential support for a new left-wing party.

Thousands of votes had leaked away from the Tories to Reform UK at last year's election, he added, and "there are similarly huge numbers of people who regard themselves as progressives and are looking for something different."

A veteran left-wing organiser, who did not wish to be named, told the BBC even with a double digit share of the national vote it is "quite hard for new parties to become positive forces in the UK".

"I think it could do quite a lot of damage to Labour and the Greens if it gets above a critical mass," he said.

Senior Greens have told the BBC they are not worried about a new insurgent party.

Green leadership hopeful Zack Polanski said "anyone who wants to challenge Reform and this failing Labour government is a friend of mine".

But he added: "In the past there's been lots of left-wing parties, but only the Green Party has endured and had sustained growth."

Polanski's point was echoed by his leadership contest rival Adrian Ramsay, who currently co-leads the party, who said anyone looking for a "progressive alternative to Labour" should join the Greens.

Any damage to the Greens could be limited by a "non-aggression" pact with the new party, running candidates on a joint ticket, for example, or agreeing to stand aside in certain circumstances.

Jeremy Corbyn has been working for some time under the radar to turn the small group of independent MPs he co-ordinates into a full-blown political party which could stand candidates at the local elections next year.

Last year, the Islington North MP united with Shockat Adam, Ayoub Khan, Adnan Hussain and Iqbal Mohamed - four independents that beat Labour candidates in the 2024 election with their pro-Palestinian stance in constituencies with large Muslim populations.

On Wednesday he hinted that a new party could be on the way, telling ITV's Peston he and his fellow pro-Gaza independents would "come together" and "there will be an alternative".

The MPs are united in their condemnation of Keir Starmer's approach to the Gaza crisis, but we don't know what their rest of their policy programme would be.

We do not even know for certain that Jeremy Corbyn would be their leader. He is thought to favour a democratic convention to decide on leadership but others in the project are impatient to get on with it.

Sultana is clearly keen to play a leading role, although her statement was carefully worded - she wants to co-lead the "founding" of a new party with Corbyn.

One thing is clear - any new party will not be a reincarnation of the previous Corbyn project, as key figures on Labour's left show no sign of leaving.

Corbyn's former shadow chancellor John McDonell said he was "dreadfully sorry to lose Zarah from the Labour Party" but is not expected to quit himself.

The chair of the Labour party under Corbyn - Ian Lavery – told the BBC he planned to stay in the party until he retired.

The Independent MPs were elected last year in areas where voters felt Labour wasn't taking a strong enough line on Israel's actions in Gaza.

We don't know how resonant the issue will be at the next election, four years away.

But where Keir Starmer's strategists might be concerned is that a new left-wing party might just reduce the Labour vote by enough in some seats to allow a second-placed Reform UK to sneak home.

And Labour may have to be more mindful that it can lose votes on the left and not just the right.

It was once seen as close to impossible to successfully launch a new political party in the UK, under Westminster's first-past-the-post voting system.

But Reform UK, which has five MPs and is currently ahead in the polls, has shown how volatile politics now is and the extent to which traditional party loyalties no longer matter.

A well-known leader and some eye-catching policies could potentially redraw the map of mainstream politics.

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