Green Party leader Zack Polanski to run in Holborn and St Pancras by-election

When Keir Starmer dramatically resigned as the MP for Holborn and St Pancras this week, all eyes quickly swivelled to Zack Polanski.

Elected as Green Party leader just a year ago, Polanski has rapidly made a name for himself. His achievements include:

• Quadrupling the party's membership numbers within six months of taking the post
• Leading the Greens to victory in the Gorton and Denton by-election
• Overseeing the party's best-ever performance in the local elections in May

A YouGov poll even put the Greens at second place, on 21%, behind Nigel Farage's Reform UK for a brief stint in March.

A Reversal of Fortunes

But what goes up must come down, as the Greens soon found out.

Polanski attracted intense scrutiny after it emerged he had failed to vote in the local elections and that he had not paid council tax while living on a narrowboat for three years — though he has since been cleared by an ethics inquiry over the latter.

The London Assembly member was then criticised for questioning the police response to the Golders Green attack online and for sharing an Instagram post of a t-shirt featuring a picture of a guillotine with the words: "We're only making plans for Nigel."

Some progressives began drifting back to Labour after Keir Starmer was replaced by Andy Burnham in July.

The Greens are now down in fourth place on 13% according to YouGov's latest poll, while Polanski himself has the lowest favourability ratings of all party leaders on 19%.

Why Stand Now?

So it's worth asking: why is he putting himself forward for a by-election now?

Polanski remains the most high-profile figure within the left-wing party, and a Green victory would be historic — making it their first ever London constituency win.

The Green leader has long said he would consider running for parliament if a London seat became available, and he wasted no time signalling his desire to be selected by local Green members as the party candidate for Starmer's former constituency this week.

While the decision is not yet final, Polanski is widely expected to be the party's choice for the crunch vote in a head-to-head with Labour.

High Stakes for Both Parties

As Sky News elections analyst Robert Ford wrote on X, the stakes are high for both parties:

"Greens have chance to turn the tide on recent decline and show Polanski is a winner. Labour have a chance to show that the Burnham bounce is real, consolidate the left in a London heartland seat, and deal a potential knockout blow to Green insurgency."

Ford added that Polanski's decision to join the contest meant it is "no longer just Green vs Lab", claiming voters are now being asked: "Would you like the national leader of the Green party or a generic Lab backbencher as your local representative?"

Green MP Hannah Spencer with Polanski after she won the Gorton and Denton by-election in February

A Precarious Position

The situation remains precarious, however, particularly as the seat is traditionally Labour.

The Greens are trying to put their best foot forward, with one party official telling HuffPost UK they feel "confident" about Polanski's chances.

Another senior insider dismissed the idea that putting the Green leader forward was risky, insisting he would be a "brilliant candidate."