The Labour leader of Haringey Council is quitting after condemning "sexist and bullying" behaviour during a bitter party battle over a controversial redevelopment scheme.
Claire Kober will not seek re-election in the north London borough in May following a long-running row over a proposed £2 billion housing project known as the Haringey Development Vehicle (HDV).
Labour leader Jeremy Corbyn has opposed the project, which has been criticised by many on the left of the party.
In an unusual move, Labour's ruling National Executive Committee (NEC) requested last week that Haringey Council call a halt to the scheme, which involves partnership with the private sector.
Ms Kober told the London Evening Standard: "The sexism, bullying, undemocratic behaviour and outright personal attacks on me as the most senior woman in Labour local government have left me disappointed and disillusioned."
Announcing on Twitter that she was standing down, Ms Kober took a thinly veiled swipe at pro-Corbyn campaign group Momentum, whose members have been active in selection battles for the forthcoming council elections.
Praising council colleagues, Ms Kober said: "I am only sorry that many have been denied the opportunity to stand once again."
Labour's shadow local government secretary Andrew Gwynne, who has been asked to mediate in the development row, said: "I am sorry that Claire Kober is standing down, she has led Haringey through a very difficult time for local government.
"The housing crisis is a national scandal caused in 10 Downing Street.
"However, there are issues specific to Haringey that have caused concern for many residents and local politicians, which is why I have been asked to mediate.
"I am committed to working with Haringey Council, its residents and local MPs, to tackle the housing crisis in the borough."
Labour former frontbencher Harriet Harman told BBC Radio 4's The World at One: "I just cannot speak too highly of Claire. I'm really disappointed that she is standing down.
"All that she says about the difficulty about being a woman in leadership I'm sure is absolutely true and is a challenge to all of us in the party, the Labour Party, which is a party of women and equality after all."
London Mayor Sadiq Khan praised the council leader, saying: "Claire deserves massive credit for the excellent job she has done turning around children's services in Haringey in the aftermath of the terrible Baby P scandal and improving local schools to the point that they are now almost all rated Good or Outstanding. "
Tory party chairman Brandon Lewis said: "From Labour headquarters to Haringey Council, Jeremy Corbyn's hard-left supporters continue their takeover of the Labour Party."
Critics of the HDV have described the scheme as "social cleansing", while Ms Kober, who has led the council since 2008, returned fire by hitting out at "ideological dogmas".
The £2 billion scheme would see the transfer of council assets and land into a 50/50 partnership with a private developer.