Britons went to the polls on Thursday in local elections that will serve as a bellwether not only for the fading appeal of legacy parties but for the electorate’s willingness to overlook accusations of antisemitism swirling around a rising left-wing force. At the centre of this test stands Zack Polanski, the 43-year-old Jewish activist who has propelled the Green Party into unprecedented prominence, at times polling ahead of Labour. A strong showing for his party would instantly make Polanski one of the most high-profile Jewish progressives globally, yet his trajectory has been shadowed by controversy over his response to the stabbing of two Jewish men in Golders Green and his questioning of Israel’s right to exist as a nation.

The controversy has not, however, branded the Greens as the party most tainted by antisemitism in the public mind. A YouGov poll conducted in the aftermath of the Golders Green incident found that Labour and Reform UK were each identified by a third of respondents as having an antisemitism problem, while only a quarter said the same of the Greens. Viewed from London, this suggests that voters are filtering the row through a broader landscape of political toxicity, with the Conservatives and Liberal Democrats trailing at 16 and 13 per cent respectively. Yet Polanski’s own ratings have suffered, particularly after an exchange with ITV’s Robert Peston in which he declared that “no country has a right to exist” and dismissed talk of national sovereignty as “semantics” at the root of the Israel-Palestinian conflict.

The paradox of a Jewish leader adopting such a position has not been lost on observers. Polanski describes himself as “certainly not a Zionist”, setting him apart from figures such as Bernie Sanders, the doyen of global progressive Jewry. Analysts in Paris, where Le Figaro recently profiled him as “l’écolo-populiste”, note that Polanski has deliberately shifted the Green Party’s focus from environmentalism to social justice and an anti-establishment stance, courting Muslim voters and positioning the party as the true left alternative to Keir Starmer’s Labour. This strategy has amplified his profile but also deepened the scrutiny on his every statement regarding antisemitism and Israel.

Looking ahead, Thursday’s results will reveal whether Polanski’s blend of charisma and ideological radicalism can withstand the backlash. If the Greens make the gains that recent polls have hinted at, he will become a fixture in British politics, challenging Labour from the left and forcing a reckoning over how progressive parties manage the fault lines of identity and foreign policy. If the vote proves more modest, the question will hang over his leadership: can a party that prides itself on tolerance afford a leader whose own credibility on antisemitism is so fiercely contested? The answer will resonate well beyond Britain’s town halls.