Zack Polanski’s leadership of the Green Party faced a fresh challenge tonight after former party MP Caroline Lucas accused him of being “missing” during the latest anti-Semitism row and declined to back his continued leadership.
Ms Lucas, who also previously led the party, criticised Mr Polanski in a television interview after he missed a weekend conference vote approving the controversial policy that equated “Zionism” with “racism”.
With polling ending tonight in the Holborn & St Pancras by-election, where Mr Polanski hopes to become the latest Green MP, she accused him of leaving the party’s conference in Brighton rather than remaining to oppose what she called a “dangerous” motion backed by hardline pro-Palestinian activists.
Green Party members voted on Sunday to approve a motion that calls for the eventual destruction of Israel and compares its treatment of the country with apartheid-era South Africa in relation to the war in Gaza.
Mr Polanski left the conference after delivering a speech on Friday to focus on his campaign in Holborn & St Pancras, where he is expected to lose to Labour.
Following the vote, he attempted to calm the backlash by joining the Green Party’s five MPs in issuing a statement distancing themselves from the decision.
Speaking on the BBC’s Newsnight, Ms Lucas, the former MP for Brighton Pavilion, said Mr Polanski “should have been there and he should have voted”. She added: “I would have hoped that he would have been a very strong critic of this motion because, in my view, it was flawed from top to bottom.”
“It is dangerous, it is divisive, and it tries to impose a single definition of Zionism when we know there are many.”
Asked whether Mr Polanski should remain Green Party leader, she replied: “Let’s see what happens in the coming days and weeks.”

Caroline Lucas, a former Green Party leader, criticised Mr Polanski on television after he missed a conference vote approving the highly controversial “Zionism is racism” policy

The embattled “eco-populist” is standing to replace Sir Keir Starmer in the north London constituency but is expected to be defeated by Labour’s Sagal Abdi-Wali in the early hours

A surprise victory would make Mr Polanski the sixth Green MP in the Commons, while a defeat—particularly a heavy one—would raise further questions about the direction he has taken the party
“I want him to explain what happened. I want him to demonstrate the leadership that was missing on Sunday. I think the jury is still out on whether he will do that, but I hope he will.”
The under-pressure “eco-populist” is attempting to unseat Sir Keir Starmer in the north London constituency, but is forecast to be defeated by Labour’s Sagal Abdi-Wali in the early hours of the morning.
If he pulls off an unexpected victory, Mr Polanski would become the sixth Green MP in the Commons. A defeat, especially by a wide margin, would intensify scrutiny of his leadership and the political direction he has chosen for the party.
The Greens enjoyed a rise in support in the polls earlier this year, but their position has since weakened following a series of gaffes and the emergence of Andy Burnham as Labour leader.
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The latest dispute is one of several controversies to engulf the party since the former actor and hypnotist became leader in September last year, shifting it further to the Left and away from its traditional ecological focus.
After the polls closed, a Conservative spokesman said: “If Zack Polanski fails to win this by-election, it will surely be curtains for his leadership of the party.
“We hope it also marks the end of the Green Party’s sorry embrace of anti-Semitism.”
The Greens, meanwhile, suggested that simply emerging as Labour’s main challenger represented an achievement.
Mr Polanski wrote on social media: ‘The Green Party got 10 per cent last time.
‘Whatever happens tonight – we made Labour work like they never have before. I’m so proud of you all.’
The Green leader had been appealing for help from activists as residents cast their ballots in the contest for Sir Keir Starmer’s old seat.

Ms Abdi-Wali is the bookies’ favourite, with confidence growing inside the party that the Camden councillor will clinch victory.
Ms Abdi-Wali is the bookies’ favourite, with confidence growing inside the party that the Camden councillor will clinch victory.
But Mr Polanski insisted on social media overnight that he ‘can win’, claiming there might be just a ‘few hundred votes in it’.
He pointed to a projection from Poll Check suggesting Labour could get 40.4 per cent of the vote and the Greens 35.6 per cent.
Defeat for Mr Polanski would underline how Mr Burnham’s arrival has flattened the Green surge – which saw them scoop Gorton & Denton in a by-election in February and then secure record-breaking local council results in May.
Holborn & St Pancras has been a Labour stronghold since its formation in 1983, held by Frank Dobson for 32 years and Sir Keir for 11.
There are 13 other candidates in the by-election, including the Conservatives’ Ewan Cameron, Reform UK’s Peter Newman and the Liberal Democrats’ Patrick Thomas Stillman.
Also running is George Galloway of the Workers Party of Britain, despite living overseas in what he describes as ‘self-exile’.
Sir Keir won the Holborn and St Pancras seat in 2024 with 48.9 per cent of the vote (18,884 votes), with independent Andrew Feinstein as runner-up on 18.9 per cent (7,312 votes) and the Greens in third with 10.4 per cent of the vote (4,030 votes).