Momentum founder Jon Lansman has dropped his bid for the vacant post of Labour’s general secretary.
On Twitter, he said he had “decided to step back from the race” to focus on his role on the party’s ruling National Executive Committee.
He said he had achieved his aim of sparking debate about the party’s governance and encouraging others to stand for general secretary.
The Labour leadership favours Unite official Jennie Formby for the role.
Mr Lansman is understood to have come under pressure from Labour leader Jeremy Corbyn to pull out of the race.