The UK’s Labour Party won a special election for a central London parliamentary seat early Friday morning, providing a boost to Prime Minister Andy Burnham and a blow to Green leader Zack Polanski.

Labour’s candidate, local council leader Sagal Abdi-Wali, got 45 percent of the vote in Holborn and St Pancras, ahead of Polanski, who came in second with almost 33 percent. The constituency was recently vacated by former Prime Minister Keir Starmer after he was deposed by Burnham, in part because Labour lawmakers hoped he could do a better job countering the Greens.

While Polanski tripled his party’s vote share from the general election in 2024, the failure to win a seat in the House of Commons still represents a major setback. After the result, he said he intended to stay on as leader.

Labour was favored to win, having occupied the seat since its 1983 inception, and party strategists are likely to take the result as a sign Burnham is reenergizing the progressive voter base that splintered under Starmer.

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Polanski had tried to persuade the liberal constituency’s voters that they’d be better served by electing the leader of a party who could push Burnham further to the left, instead of giving Labour another backbencher to boost its majority in the 650-seat House of Commons. Polanski currently serves as a member of the London Assembly and was looking to transition to the Parliament in Westminster, where his party is represented by a contingent of five MPs.

Labour’s nationwide popularity had slipped precipitously since Starmer led it to a majority in 2024, but polling shows it’s enjoying a bounce under Burnham. The by-election is the first to be held since he became premier in July, and takes place in a constituency encompassing prestigious universities, many of London’s legal offices, and the British Museum.

The new prime minister has refocused his party toward an unabashedly left-wing agenda that prioritizes public ownership. He has proposed trimming rises in the state pension in order to fund a care service for the elderly that operates along the same principles as healthcare, which in the UK is free at the point of use.

In her acceptance speech, Abdi-Wali praised her predecessor Starmer and said she wants to work with Burnham to bring Thames Water into public ownership and fight street homelessness. While in its northern reaches, Holborn and St Pancras contains some of the most affluent parts of London, several of its neighborhoods are counted among the most income-deprived in England.

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“I will fight for a water system that puts public interest first and gives people the confidence that essential services are being run for them,” Abdi-Wali said.

Missing out on a seat in the House of Commons will be a blow for the Greens, even while officials managing expectations in advance of the vote pointed out that Nigel Farage, leader of right-wing party Reform UK, stood unsuccessfully in seven parliamentary elections before gaining a seat.

The Green leader came into the vote facing blowback after his party passed a controversial motion at its annual convention last week to class Zionism as racism, a move that some members worried would put off center-left voters.

But Polanski, who said he grew up in a Zionist household, appeared to signal support for it. “What we’re seeing is an ongoing genocide and the displacement of the Palestinian people,” he told Sky News. “I believe that’s clearly racist.”

While he’s been credited with tripling the Greens’ membership to more than 200,000 people since he became leader just over a year ago, his popularity ratings have dipped in recent months.

Alongside the flagging poll ratings of the right-wing insurgents led by Farage, who have been hampered by scandals over campaign financing, that’s emboldened Labour and the Conservatives, who used their own recent conventions to espouse policies that indicate they’re keen to fight the next election along left-right lines.

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“Any ideas of a return to the cozy two-party system is just wishful thinking on the part of the establishment,” the Green Party wrote in a statement after the result.

Labour’s energy secretary is due to make a contentious call on whether to permit new drilling at the Jackdaw and Rosebank gas and oil fields in the North Sea. A decision to go ahead could reenergize the Greens, who have traditionally centered a climate agenda.

“So they want to give Andy Burnham a chance,” Polanski told Sky News after the result. “Well, they’ve got a chance now. Let’s see what he does with it.”