“Enough is enough,” Jewish groups have said in a letter accusing Jeremy Corbyn of failing to tackle anti-Semitism.
The Labour leader has said he is “sincerely sorry” for the pain caused by “pockets of anti-Semitism” in the Labour Party.
Mr Corbyn said he would be meeting representatives of the Jewish community to “rebuild” confidence in his party.
However, the organisations behind the open letter are planning a protest outside Parliament later.
The letter – drawn up by the Board of Deputies of British Jews and the Jewish Leadership Council – said there has been a “repeated institutional failure” to properly address anti-Semitism.
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It accuses Mr Corbyn of being unable to “seriously contemplate anti-Semitism, because he is so ideologically fixed within a far left worldview that is instinctively hostile to mainstream Jewish communities”.
The organisations refer to Mr Corbyn’s apparently supportive message to the creator of an allegedly anti-Semitic mural in 2012 and his attendance at “pro-Hezbollah rallies”.
They say the Labour leader has “sided with anti-Semites” either because of “the far left’s obsessive hatred of Zionism” or “a conspiratorial worldview in which mainstream Jewish communities are believed to be a hostile entity, a class enemy”.
The letter says those who push anti-Semitic material view Mr Corbyn as “their figurehead” and that he is “the only person with the standing to demand that all of this stops.”
The letter will be delivered to a meeting of Labour MPs and peers, although the Labour leader is not expected to attend.
A protest will then be held outside the Houses of Parliament, which will see a number of Labour MPs – including Liz Kendall, John Woodcock and Ian Austin – join members of the Jewish community.
The Campaign Against Anti-Semitism group has also called for a national protest against anti-Semitism in Labour.
Labour MP Louise Ellman, former chairwoman of the Labour Jewish movement, said: “It’s taken Jeremy far too long to admit how wrong he has been in failing to deal with anti-Semitism in the Labour Party.”
She told BBC Breakfast the Labour leader now had “to act and he’s got to root out the anti-Semitism that is within the Labour Party”.
“It’s just heartbreaking to see it but he has got to do something about it now. Words won’t be enough,” she added.
In a statement released on Sunday evening, Mr Corbyn said: “I want to be clear that I will not tolerate any form of anti-Semitism that exists in and around our movement.
“We must stamp this out from our party and movement.
“We recognise that anti-Semitism has occurred in pockets within the Labour Party, causing pain and hurt to our Jewish community in the Labour Party and the rest of the country.
“I am sincerely sorry for the pain which has been caused.”
Mr Corbyn said he and the party – which has “deep roots in the Jewish community” – were now campaigning to “increase support and confidence in Labour” among Jewish people in Britain and he would meet members of the community in the coming days to “rebuild confidence”.
What caused the row?
In October 2012, street artist Mear One posted a picture of his mural in east London called “Freedom of Humanity” on Facebook – which depicted businessmen, some of them the artist says are Jewish, counting money on a board game that is balanced on the backs of hunched-over men.
The artist wrote: “Tomorrow they want to buff my mural. Freedom of expression. London calling. Public Art.”
Mr Corbyn replied: “Why? You are in good company. Rockerfeller destroyed Diego [Rivera’s] mural because it includes a picture of Lenin.”
More recently, Labour MP Luciana Berger sought clarification from the leader’s office on the 2012 comments.
Mr Corbyn said he regretted not looking more closely at the image, which he called “deeply disturbing”.
He added: “I am opposed to the production of anti-Semitic material of any kind, and the defence of free speech cannot be used as a justification for the promotion of anti-Semitism in any form.”
Mear One – whose real name is Kalen Ockerman – has denied being anti-Semitic, saying the mural was about “class and privilege”.
Jonathan Goldstein, chairman of the Jewish Leadership Council, said the community had had enough of being ignored by Mr Corbyn.
He told BBC Radio 4’s Today programme: “This is the first time in my lifetime the Jewish community has felt the need to take to the streets to campaign against the leader of a major political party.
“Rightly or wrongly, Jeremy Corbyn is now the figurehead for an anti-Semitic political culture based upon obsessive hatred of Israel, conspiracy theories and fake news, and that is doing great harm, not just to the Labour Party, but to Britain in a wider sense.”
The BBC’s assistant political editor Norman Smith said what was extraordinary about the letter was “not just the raw anger… but the fact that they directly blame Jeremy Corbyn and his brand of politics for allowing anti-Semitism to get a hold in the Labour Party”.
“They accuse [Mr Corbyn] of a far left world view which they say is instinctively hostile to mainstream Jewish communities,” he told Today.
“What they mean by that is a view of Israel as inherently a sort of neo-colonialist, imperialist power oppressing Palestinians, associated with America, and it is that sort of politics that has allowed anti-Semitic views to gain a hold.”
However, he added, Mr Corbyn supporters believe that claims of anti-Semitism are “ridiculous and absurd”, given the leader’s anti-racism record, and that those making the accusations are using it to attack him.
In 2016 an inquiry into anti-Semitism in the Labour party, led by Shami Chakrabarti, said the party was not overrun by racism but there was “too much clear evidence… of ignorant attitudes”.
It followed the suspension of MP Naz Shah and ex-London mayor Ken Livingstone amid anti-Semitism claims.