The Green party is just four points behind Labour in urban constituencies, putting them within touching distance of taking as many as 40 seats if the result was replicated at the next election. This was reported by Qazaqyia.kz citing The Guardian.

The survey by ThinkLabour, which has extensive links to Andy Burnham's government, finds that urban voters have moved in large numbers towards Zack Polanski's party since the 2024 general election. The research highlights the challenge Labour faces holding onto the Holborn and St Pancras seat in the face of a challenge from Polanski himself at next month's byelection.

The study's authors warn that evidence from previous electoral battles between the two parties suggests Labour politicians should dial down direct attacks on the Greens for fear of looking like they are "kicking a puppy".

Christabel Cooper, one of the report's authors, said: "The previous administration [under Keir Starmer] had always banked on the fact that Labour would be able to say to people who vote Green that they would get Nigel Farage as prime minister. But in the 40 seats that we have identified, that is no longer the case – the Greens can claim to be the progressives' party of choice."

She added that evidence from other elections where the party has gone head to head with Labour suggests that progressives dislike aggressive attacks on the Greens.

"The sorts of people who would consider voting Labour consider attacking the Greens like kicking a puppy. They think, we are all supposed to be nice and liberal, why are we having a go at the Greens?"

The findings, which have been discussed with strategists in No 10 as they look to solidify separate polling gains made in Burnham's early weeks as prime minister, show Labour faces a difficult task winning back urban progressives who helped the party win the last election.

ThinkLabour's former chief executive Alison Phillips is now Burnham's chief of staff, while other alumni of the organisation have senior roles across government.

The research was carried out as Burnham was about to take office in Downing Street, meaning it will not have captured the full effect of the "Burnham bounce", which has seen Labour gain ground with progressive voters and pull level with Reform UK.

The poll shows that support for the Greens has increased by 12 points in major cities since the general election, while Labour's vote share has fallen by 20 points, leaving Labour only 4 points ahead in some of its most reliable strongholds.

It found that the move away from Labour to the Greens has been more pronounced among voters who are financially struggling, undermining the stereotype of Green voters as affluent liberals.

The report warned that urban voters felt they did not know what Labour's values were, in part because of some of the counterintuitive measures taken by Starmer in his early days as prime minister, such as cutting winter fuel payments.

It also warns that winning these voters back will mean focusing immigration reforms on tackling small boat crossings rather than wider measures to tackle legal migration as well.

Shabana Mahmood, the home secretary, is bringing in measures to make it harder for legal migrants to achieve settled status, which have proved controversial with Labour MPs and activists.

The report said: "On divisive areas such as immigration, where liberals and social conservatives can agree on some outcomes – reducing small boat crossings, for example – it should primarily focus on these. Where its policies appear tough or restrictive, Labour must be able to make a convincing progressive case for them, showing how they solve practical problems rather than simply signalling to the right."

The researchers also found that attacks on the Greens over foreign policy had the most effect with the voters Labour is trying to win back, in part because they found these more credible than other criticisms.

While urban voters did not like Green policies on legalising drugs – which Labour focused on during the failed campaign to win the Gorton and Denton byelection – they did not view them as a particularly credible threat.

Personal attacks on Polanski, meanwhile, went down badly among those considering voting Green, who viewed criticisms of his CV and his past as a hypnotherapist as especially non-credible.

The Green leader has previously come under fire for telling a journalist in 2013 he could enlarge women's breasts with hypnotherapy – comments he has since said he regrets.