Leftwing Labour MPs including John McDonnell are urging colleagues, “don’t leave, organise”, as the sacking of Rebecca Long-Bailey provides a rallying point for critics of Keir Starmer’s leadership. McDonnell and Jeremy Corbyn were among MPs who met Starmer on Friday morning to express their concerns. The Labour leader is facing a backlash from leftwingers in the party after abruptly removing Long-Bailey from her post as shadow education secretary on Thursday. At Friday’s meeting, held via video link, Corbyn urged Starmer to continue to take a tough line on the annexation of Palestinian territory, and to meet the leftwing group Jewish Voice for Labour. JVL supported Corbyn when he faced claims of failing to tackle antisemitism during his leadership. Part of Corbyn’s contribution to Friday’s meeting was obscured by a poor internet connection. McDonnell later approvingly tweeted details of a grouping called Don’t Leave, Organise, of which JVL is a member. Set up in the spring, the group says its aims include “to prevent any rightward drift that may occur within Labour under Keir Starmer”. With Starmer already narrowly holding a majority on Labour’s ruling national executive committee (NEC), some are concerned about tens of thousands of members leaving the party, weakening the voice of the left inside the Labour machine. Long-Bailey’s removal on Thursday prompted criticisms from leading leftwing figures in the party, some of whom had previously been reluctant to confront Starmer directly. Long-Bailey had tweeted a newspaper interview with Maxine Peake, calling the actor an “absolute diamond”. In discussing the Black Lives Matter movement, Peake linked the behaviour of US police with Israel – something Starmer called an “antisemitic conspiracy theory”. Peake, a longtime Labour supporter, subsequently apologised. The general secretary of the Unite union, Len McCluskey, tweeted that Starmer’s decision was “an unnecessary over-reaction to a confected row”, adding that “unity is too important to be risked like this”. Corbyn has adopted a relatively low profile since stepping down from the leadership in the wake of December’s general election defeat. But Friday’s meeting underlines the fact that a well-organised leftwing caucus has been preparing to act as a focal point for dissent against Starmer’s leadership. The former deputy leadership candidate Richard Burgon has been building up the profile and resources of the Socialist Campaign Group, with the backing of McDonnell, the former shadow chancellor and Corbyn’s close ally. Burgon’s allies say he wants to make it into a leftwing version of the Fabian Society. In a statement released after the meeting, the Socialist Campaign Group said it had been “a business-like exchange of views”, which as well as Long-Bailey’s sacking had covered “the need for the Labour party, MPs, party members and supporters to speak out about Israel’s illegal annexation and ongoing human rights abuses by the government of Israel”. They later released a separate statement, signed by 21 MPs including Corbyn, McDonnell and Diane Abbott, saying: “In line with conference policy, Labour must recognise that any just peace must be based on self-determination for Palestine, with equality and human rights for all.” Corbyn’s allies have long felt that pressure over antisemitism has been used as a way of silencing legitimate criticism of Israel. An “emollient” Starmer told them, according to one witness, that he had no intention of letting that happen – and had been fighting for human rights throughout his life. Labour insiders also point to the fact that Lisa Nandy, the shadow foreign secretary, has been part of a cross-party group pressing for an urgent question in the House of Commons on annexation, with a draft expected to be submitted to the party – and to named individuals – imminently. Long-Bailey’s sacking has rekindled tensions over Labour’s record on antisemitism under Corbyn’s leadership, which is under formal investigation by the Equality and Human Rights Commission (EHRC). An internal report leaked over Easter and apparently prepared for submission to the EHRC, blamed a “hyper-factional culture” at Labour HQ during the early years of Corbyn’s leadership for some of the party’s failings during that period. Starmer launched a review into the contents of the report, which included scores of strongly worded personal WhatsApp messages sent by staffers hostile to Corbyn, and how it was leaked. Chaired by the QC Martin Forde, the review panel launched a call for evidence on Friday. Forde said he could not compel people to come forward, but urged them to do so. “We cannot force anyone to bring information to us but I hope all those with an interest in the issue will see the value of contributing. That way we can build the fullest picture of the circumstances and content of the leaked report as well as the current culture and practices of the Labour party,” he said. The review’s terms of reference, also published on Friday, say issues it will examine include: “The extent of racist, sexist and other discriminatory culture within Labour party workplaces, the attitudes and conduct of the senior staff of the Labour party, and their relationships with the elected leadership of the Labour party.”