Green Party leader Zack Polanski has failed in his bid to become an MP, with a narrow loss in the Holborn and St Pancras by-election.
Voters in the seat, which was held by ex-PM Sir Keir Starmer before his resignation last month, instead decided to stick with Labour.
Victorious candidate Sagal Abdi-Wali, the leader of Camden Council since May, secured 12,292 votes to Polanski’s 8,928.
The by-election was seen as a major test of new prime minister Andy Burnham’s appeal in London, where Labour’s support collapsed under Starmer.
In May’s local elections, the party lost control of 10 councils in the capital – though it stayed in control of Camden, which closely matches the area where Thursday’s election took place.
Long before the former PM announced his intention to step down from the House of Commons, Polanski singled out Holborn and St Pancras as a seat he had his eye on.
It was seen as the kind of diverse, urban constituency that his party could pinch from Labour amid the boost in polling and membership that followed Polanski’s election in October last year.
But the Green leader has faced mounting pressure in recent weeks over falling poll numbers for his party and the decision by members to oppose two amendments he supported in a controversial vote to oppose an Israeli state.
His loss in the north London seat may prompt his opponents in the party to question whether a new direction is needed.
The Green Party conceded the by-election at around 2.30am.
After the defeat was confirmed, a spokesman said the party is ‘here to stay and just getting started’.
He added: ‘Achieving a huge swing in one of Labour’s safest seats – an increase of 22% in vote share since the General Election – is an incredible result for the Green Party, and during a honeymoon period for the new PM.
‘We are disappointed to miss out tonight but any ideas of a return to the cosy two-party system is just wishful thinking on the part of the establishment.’
Polanski succeeded in significantly cutting back Labour’s lead in the seat – though turnout was just 39%, considerably lower than the two recent by-elections in Clacton and Makerfield.
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