In early September, Zarah Sultana made a bold announcement. “Labour is dead,” the 31-year-old socialist member of Parliament told a crowd of hundreds gathered in Newcastle. She had left Britain’s ruling party only in July, pledging to “co-lead” a new left-wing party with Jeremy Corbyn, a former Labour leader who was expelled last year. More than 700,000 Britons have signed up to the mailing list of the provisionally titled Your Party. Among the party’s goals are redistributing wealth, taxing the very rich, making rail and energy publicly owned, standing up to fossil-fuel giants, and ending arms sales to Israel.

Sultana was perhaps too quick to declare Labour’s demise, but she had reasons to forecast it. Although he won a landslide victory last year, the Labour leader Keir Starmer has already disappointed many supporters. In polls, he has fallen behind the right-wing Reform UK of Nigel Farage. As progressives have done with center-left leaders elsewhere, many would-be supporters have deemed him to be insufficiently pro-Palestine. Additionally, he has cut welfare benefits and centralized control of the party. Dozens of councilors around the country have left Labour since last year. In Newcastle, Sultana shared the stage with Jamie Driscoll, a popular regional mayor who left the party in 2023 after Labour passed him over as a candidate for mayor of the North East.

And yet, for all the buoyancy onstage, Sultana’s party was already riven with deep divisions and suffering from self-defeating impulses familiar to observers of the American progressive left. If Your Party means to empower the British left rather than delivering elections to Labour’s rivals to the right, it has some soul-searching to do.

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The rifts within t