Pro-Jeremy Corbyn campaign group Momentum will make moves to remove its vice-chairwoman Jackie Walker from her post next week, in a row over anti-Semitism.
Ms Walker is facing mounting calls to resign over comments made at an anti-Semitism training event run by the Labour Party.
The steering group of Momentum, which rose from the campaign to get Mr Corbyn elected as Labour leader last year, meets on Monday.
And a spokesman for the group confirmed that senior figures wanted to oust her.
A spokesman for Momentum said: “Members of Momentum’s steering committee are seeking to remove Jackie Walker as vice-chair of the committee.”
Ms Walker has come under fire after leaked footage of the training event showed her saying she had not found a definition of anti-Semitism she could work with.
The footage also showed her questioning why Holocaust Memorial Day was not more wide-ranging to include other genocides.
Ms Walker was previously suspended from the Labour Party for comments on social media saying Jews were the “chief financiers of the sugar and slave trade”.
She was readmitted to the party after an investigation.
Commenting on Jackie Walker’s recent outbursts, John Mann MP said: “Enough is enough. Though she claims impunity for many reasons, Jackie Walker’s behaviour is discriminatory, provocative, offensive and by any standard unacceptable in a modern political party.”
“Not only has she caused offense personally, she has inspired waves of antisemitic and racist backlash including Holocaust denial. Not only must she be expelled from the Labour Party immediately but all those abusing others in supporting her must go too.
“Temporary suspensions are not good enough, these people must be given permanent bans and no platform to express their antisemitism anywhere in the Labour Party, if we are to be serious about opposing anti-Jewish hatred.”
Trade union TSSA has threatened to remove its support of Momentum if veteran activist Ms Walker remained in post.
Its general secretary Manuel Cortes said: “I am deeply saddened that a fellow member of our Labour and trade union family holds such anti-Semitic views.”
Ms Walker has previously apologised for any offence caused, and defended herself in an interview on Channel 4 News.
When she was asked whether she had considered resigning given the outrage among some Jewish groups, Ms Walker said: “Some other prominent Jewish groups, of which I’m a member of, think a very different thing.
“What we have to look at when we’re talking about this subject, particularly at the moment, is the political differences that are underlying this as well.”
Ms Walker said whoever leaked the footage from a Labour Party anti-Semitism training event “had malicious intent in their mind”.
She also said she was anti-Zionist rather than anti-Semitic, adding: “I think Zionism is a political ideology, and like any political ideology, some people will be supportive and some people won’t be supportive of it. That’s a very different thing.”
Other points raised by Ms Walker included querying why the Holocaust only marked genocides that happened after the Nazis.