London —
Keir Starmer has thrown down the gauntlet to his potential rivals, defying calls to quit as Britain’s prime minister and instead challenging his would-be opponents to launch a formal challenge against his leadership of the Labour Party.
To trigger a leadership challenge, one fifth of Labour’s members of parliament (MPs) – that is, 81 lawmakers – must coalesce around a single candidate. Once one or more candidates amass that level of support, their names can be put on the ballot to run against Starmer, in a contest voted on by Labour Party members.
Despite nearly 100 lawmakers publicly urging Starmer, 63, to quit, no candidate has yet mounted a formal leadership challenge against him. There are thought to be just a handful of names capable of mustering the required 81 signatures.
Here’s a look at who they are.










