Green Party leader Zack Polanski has been selected as the party's candidate for the by-election in Holborn and St Pancras, the former parliamentary seat of Sir Keir Starmer. Mr Polanski, who is a London Assembly member, will stand on 8 October.
Members of the Camden Green Party voted for Mr Polanski over local councillor Hamza Chowdhury. Green MP Hannah Spencer announced that members had "overwhelmingly" chosen Mr Polanski.
Mr Polanski stated that the Greens "might be the underdog in this election but we have the momentum and we can win." He also said he is "confident but not complacent" about his chances.
The by-election is an early test of Prime Minister Andy Burnham's popularity and Labour's ability to defend inner-city constituencies against the Green Party. Labour has held the Holborn and St Pancras seat since its creation in 1983.