On launching his campaign to succeed Sir Keir Starmer as MP for Holborn and St Pancras in north London last month, Zack Polanski was adamant that the Green Party was ready to seize one of Labour’s safest seats.
“We know we can win here,” proclaimed the leader of the Greens, at the start of his bid to win a place in the House of Commons for the first time.
One month on and Polanski sounds much less sure. Bookmakers give him a less than 12 per cent shot of winning the by-election on Thursday, and have lowered the odds on Labour so far that its implied probability of victory has reached 95 per cent.
After sliding in opinion polls over the summer, Polanski has claimed in recent days that losing the contest would not undermine his authority as leader “whatsoever” — despite simultaneous criticism by Jewish leaders that his party has stoked antisemitism.
A controversial “Zionism is Racism” motion was backed by party members on Sunday at the Greens’ conference in Brighton, even as four of its five MPs opposed it.
Polanski stopped short of encouraging members to vote the motion down and ultimately did not vote on it himself, leaving the conference early to campaign in London.
In the wake of the vote, two Green councillors have resigned and a group of Labour MPs has asked police if they should investigate whether antisemitic offences were committed at the gathering. Israel has barred Polanski, who is Jewish himself, from ever visiting the country.
Some senior party figures accuse Polanski of failing to take on the Greens’ most radical activists, and fear that the newcomers’ focus on the war in Gaza risks overshadowing the party’s traditional environmental message.
“The feeling is the by-election is going to be very hard to win now,” said one senior Green member. “I don’t think Zack will face any challenge to his leadership in the short term if he loses, but I do think there will be growing calls for a reset on strategy and direction.”
It is a long way from where the Green Party was in February. A shock victory in the Gorton and Denton by-election in Greater Manchester for Hannah Spencer, the party’s fifth MP, came as the Greens surged to almost 20 per cent in opinion polls — not far behind Labour at the nadir of Starmer’s premiership.
Their polling has almost halved since, amid questions over Polanski’s popularity and perceived trustworthiness with voters, while Labour has enjoyed a bounce in support under Andy Burnham.
The new prime minister has taken a tougher stance towards Israel than his predecessor, and a resounding win for Labour would raise party morale after it lost several London councils to the Greens in local elections in May.
But a loss to the Greens would risk undermining the ruling party’s belief that Burnham can win back leftwing voters.
Green activists in Holborn and St Pancras, a broadly progressive but socioeconomically divided constituency, remain buoyant. They believe their local campaigning muscle retains the potential to beat Labour’s candidate, Sagal Abdi-Wali, a Somalia-born refugee and local councillor.
Faruk Haroon, who was leafleting for the Greens in the seat on Monday, said the amount of “name recognition” Polanski had was “pretty amazing”, and that social housing and high rents were the main topics raised on doorsteps.
Some voters had been “lifted” by the “Zionism is Racism” motion’s backing for a single Palestinian state, Haroon said, while echoing the leadership’s pledge that it would not discriminate against Jewish members.
“You’ve got people who aren’t ordinarily engaged in politics coming up to us, wanting to actually take leaflets,” Haroon said. “It’s all to play for.”
“Now is the time to get out on the doorsteps,” Polanski said in a video posted on Instagram on Monday.
Labour officials said they were “upbeat” about the by-election but taking “nothing for granted”, describing their campaign as “positive vibes only” rather than engaging rivals.
“We haven’t spoken about the Green Party at all,” one said. “We are expecting a significant presence on the ground on polling day.”
The make-up of Holborn and St Pancras, where Starmer won nearly 49 per cent of the vote in 2024, arguably makes it more difficult to call than the bookmaker odds suggest.
Starting in central London, and capturing a swath of student accommodation south of King's Cross station, it stretches into wealthier north London areas such as Kentish Town.
Just over a fifth of the constituency’s population said they were Muslim at the 2021 census, with about a third identifying as Christian, while Jews make up 2 per cent.
Social housing and private rentals are far higher than the national average at 43 per cent and 32 per cent respectively. At the Green conference, Polanski promised a rent cap if the party ever won power nationally.
Activists said they were seeking to recreate the “carnival” atmosphere of Gorton and Denton, with local Green members opening up their homes to campaigners from further afield.
One Green leaflet distributed on Monday said the party was endorsed by the Camden Muslim Alliance and The Muslim Vote UK — both voter mobilisation groups — and carried a message in English, Bengali and Somali of “affordable housing, safer streets and for Palestine”.
Another leaflet, only in English, talked about “housing”, “safety” and “climate”.
Mark Shayler, an environmental consultant who works in the constituency, said he had flipped between Labour and the Greens “all of my life” but was leaning back towards Labour.
“On the back of the conference, it’s a mess and a pickle, and he [Polanski] is offending more people than he’s bringing with him,” Shayler said. “It’s a by-election that’s a sign of the times — it’s a by-election of populism, and that worries me because it’s the wrong way for politics to go.”