The Green Surge: Built to Last? 

Francisco Tome-Goavert, Intern
03/06/2026

The 7 May elections were the first real test of a Green Party repositioned under Zack Polanski. Their standing in the polls had risen from 10% when he was elected leader last September to 17% by polling day, delivering them 411 councillors, majority control over five councils, the mayoralties of Hackney and Lewisham, and 15 MSPs and two Senedd seats in Scotland and Wales respectively.

Having previously campaigned heavily on the environment, Polanski has shifted the Greens to take advantage of political discontent to Labour’s left. A platform emphasising wealth redistribution, renationalisation and criticism of the State of Israel has helped to deliver significant inroads in previously rock-solid Labour inner city strongholds, based on a coalition combining young urban renters, disillusioned older middle-class former Labour supporters, long-term Green voters who prioritise environmental issues, and Muslim voters. The collapse of the ‘Your Party’ project has also provided a significant boost in clearing this political space for the Greens, at least in England.

Looking at where the Greens have been successful over recent years reflects how their support base has evolved. Mid Suffolk – which in 2023 became the first majority-controlled Green council in the UK – represents the older voter base: non-metropolitan, environmentally motivated, and ex-Liberal Democrat in character. The same can be said of the two rural Westminster seats – Waveney Valley and North Herefordshire – that the Greens gained from the Conservatives in 2024.

Elsewhere, areas such as Hastings, Norwich, and the London boroughs where the Greens made significant advances last month, represent something very different: urban spaces where Labour has hollowed out and the Greens are filling the gap on a left-wing economic and pro-Gaza platform. The profile of these areas more closely matches that of the three other Westminster seats who currently have Green MPs – Brighton Pavilion, Bristol Central, and Gorton and Denton.

Even if the Greens are prepared to jeopardise their foothold in rural areas for the potentially greater reward of being the principal left opposition to Labour in diverse urban centers, is this a durable strategy? With the Government facing multiple headwinds looking ahead to the autumn, it could well be, and the Greens may end up as kingmakers after the next election having won dozens of seats. However, here are three reasons why they may struggle to sustain recent momentum, all of which should give party strategists pause for thought.

First, the Greens have become a natural avenue for voters disgruntled with the perceived rightward drift and internal chaos of the Labour Party under Sir Keir Starmer. The potential election of Andy Burnham as Labour leader as somebody who can better communicate the progressive elements of the Government’s agenda, even if he doesn’t (as now appears possible) move Labour significantly to the left on policy, could lead to new Green voters with a strong history of voting Labour drifting back to the party. Even if Burnham loses Makerfield, a Prime Minister Rayner or Miliband would likely produce a same dynamic.

Second, while Polanski’s personal popularity has been a significant factor in the Greens’ recent success, the recent withdrawal of their first candidate for the Makerfield by-election, and over 30 antisemitism investigations relating to local government candidates, show the party needs to do much more to professionalise. The Greens also need to show they can manage the increased scrutiny that the party – and Polanski personally – will get now they’re seen as a more impactful political force, something that is far from evident in the response to the recent controversy over alleged non-payment of council tax.

Finally, the Greens face the challenge which all smaller parties must grapple with when navigating the first past the post electoral system. Polling in the mid-teens could leave them vulnerable to the fate UKIP faced in 2015: performing respectably almost everywhere but without enough of a concentration of votes to convert into a significant number of seats.

The Liberal Democrats have shown how a modest national vote share can be translated into significant gains through ruthless targeting of their priority seats, but this is based on decades of local activism and knowledge of who and where their target voters are. With the Greens’ rise in the polls and surge in membership taking place in such a short space of time, a major challenge for the party will be how they organise and effectively prioritise resources locally, to effectively convert polling success into much greater Westminster representation. This will be particularly pressing if a snap election is called before 2029.