The Green Party has experienced a notable surge in public support since the election of Zack Polanski as its leader in September 2025, with polling averages indicating a rise of four percentage points. This upward trajectory, often referred to by party insiders as the "Polanski effect," highlights a significant shift in the UK's increasingly fragmented political landscape.
Polling Disparities and Rising Support
The Guardian's latest poll tracker, which aggregates data from the past ten days, places the Greens at 13.5% nationally. This positions them just five points behind the Labour Party, which currently stands at 18.6%. However, experts caution that there is considerable variation across different polling companies regarding the exact level of Green support.
Recent surveys from YouGov and Find Out Now in January showed the Greens polling at 17%, a figure significantly higher than those reported by Focaldata, More in Common, and Survation, which all placed the party between 10% and 11%. This discrepancy may stem from methodological differences, such as whether pollsters include the Greens as an explicit option in their questionnaires or rely on larger modelling assumptions about voter behaviour.
Shifting Voter Allegiances
Analysis of YouGov data reveals a striking trend: approximately 20% of individuals who voted Labour in the 2024 general election now indicate they would support the Greens. This represents a substantial increase from the 11% recorded when Polanski initially assumed leadership. Professor Sir John Curtice of the University of Strathclyde observed, "The polls disagree by how much, but the Greens have added to Labour's woes. Already there was the case that Labour's vote was scattering in all directions, and now that's even become clearer in a post-Polanski world."
Age demographics play a crucial role in this shift. Young voters aged 18 to 24 are not only the most likely demographic to support the Greens but have also swung towards the party most dramatically in recent months. YouGov polling indicates that support among this group surged from 26% in early September last year to 45% by mid-January. Curtice noted that this appeal to young, middle-class professionals, particularly concentrated in London, could severely impact Labour's performance in the upcoming local elections.
Key Issues Driving Green Support
While the cost of living remains the primary concern for all Green supporters, there are notable differences between existing party voters and those who have recently switched allegiance. New Green voters place greater emphasis on the economy and Brexit compared to established supporters, while showing less concern about the Gaza conflict. Climate change, traditionally a cornerstone of Green policy, is prioritised by 12% of existing supporters but only 7% of new converts.
Adam McDonnell, Head of UK Political and Academic Research at YouGov, commented, "There isn't much difference between those who already voted Green at the last election and those they've gained since, with both groups highlighting the cost of living, the NHS and the environment as top concerns. Those who didn't vote Green in 2024 but now intend to place a higher weight on the economy in general."
Polanski's Personal Standing and Party Positioning
Despite the party's polling gains, Polanski's personal favourability ratings present a mixed picture. Ipsos polling indicates his net favourability stands at -15 points, with 20% viewing him favourably against 35% unfavourably. However, this places him ahead of most national political leaders except Liberal Democrat leader Ed Davey, largely because 45% of the public remain undecided or unfamiliar with him.
Joe Twyman, Founder and Director of Deltapoll, highlighted the Greens' positioning as an anti-establishment alternative: "There is a desire for a new political movement because the 'old guard' have been seen to have failed. You have options for nationalist parties, but if you want proper challengers on a national level, it's either Reform or Green – and it's the Greens if you're more socially liberal."
Electoral Implications and Future Challenges
More in Common's latest MRP (multi-level regression and post-stratification) modelling suggests the Greens could secure over 30% of the vote in 16 constituencies, with nine projected wins. These gains are primarily expected in urban areas such as Bristol, Manchester, and Sheffield, where the party is positioning itself as the progressive alternative to Labour.
The analysis also reveals significant potential for tactical voting, with 179 seats where combined Lib Dem, Green, and Labour vote shares exceed those of Conservatives and Reform. In forty of these, either Reform or Conservatives are forecast to win, with the Greens being the largest progressive party in eight.
Looking ahead to May's local elections, particularly in London, Green gains would signal their ability to attract the progressive voters necessary for broader electoral success. The party has also announced a major campaign push for the Gorton and Denton byelection, further testing their national appeal.
Twyman emphasised the uncertainty surrounding the Greens' ability to convert polling numbers into actual votes: "The key question is how those parties – Reform and the Greens – will be able to convert good polling numbers into actual voters come the next general election. Up until now previous general elections strategies have been based on specific constituencies, but if you have wider ambitions you have to broaden to a national campaign."
As the political landscape continues to evolve, the Greens' surge under Polanski's leadership represents both opportunity and challenge, with their capacity to build a national party machine and sustain momentum remaining crucial unanswered questions.
