Starmer stood down from the House of Commons this week, saying he wanted to devote more attention to international affairs. He quit as prime minister earlier this year after losing support in his own party, and has been succeeded by Andy Burnham. No date has yet been set for the contest.
Polanski will still need to be selected by local Green Party members. That selection is expected to take place next week.
In a taste of his campaign pitch, Polanski said “voters will have someone who will always fight their corner — never scared of big donors or the party whip.”
And he charged: “Too often Labour has stood up for corporations and big money. I will stand up for people struggling to pay their bills.”
Polanski has overseen a boost to the Green Party membership and led his party to a strong performance at the local elections in May, but has faced scrutiny around the vetting of candidates and his social media posts. He has been a member of the London Assembly scrutinizing Mayor Sadiq Khan since 2021.
Starmer held the Holborn and St Pancras seat in 2024 with an 11,572 majority, but faced a strong challenge from a left-wing independent and the Greens.