Keir Starmer’s office has begun polling British Muslim voters amid growing concern in senior Labour ranks about the damage done to their core vote by the row over the party’s position on the Middle East. Labour sources have told the Guardian that the party is running polls and holding focus groups around the country after senior officials became concerned they were losing support among one of their staunchest bases of support. The outreach effort is just one aspect of how the Middle East crisis has transformed the party in the last few months. MPs who care about the issue have established new groups to lobby Starmer, while the leader’s office has been forced to rethink how it communicates with parts of the party who say they have long been ignored. One senior Labour MP said: “Muslims are not only predominantly Labour supporters but they are also geographically important. There are many of them in a range of key target seats in both the south and the north-west, and we need to pay attention to that.” A frontbencher said: “We know we’ve lost the Muslim vote and at the very least their trust. The Muslim community is no longer a safe voter base for us because of how we initially responded to the war. So we’re just focused on damage control. We all know it.” A party spokesperson said: “Keir Starmer, the shadow cabinet and senior staff engage with colleagues both in the parliamentary Labour party and the wider party on this important issue. “The Labour party with Keir Starmer is committed to working alongside international partners to recognise the state of Palestine alongside the state of Israel, as part of efforts to contribute to securing a negotiated two-state solution.” The war between Israel and Hamas first triggered a crisis for Starmer when he gave an interview in October in which he said Israel had the right to withhold power and water from Gaza. He later reversed that position, but he angered many of his MPs and supporters again when he refused to back calls for a ceasefire. Tensions boiled over when 56 Labour MPs defied party orders and voted for a Scottish National party motion in the Commons calling explicitly for a ceasefire. That vote brought the resignation of eight of Starmer’s frontbench in the biggest rebellion of his leadership to date. But it also prompted Labour MPs to start new groups and re-establish old ones in an attempt to better organise the way in which they petition the leadership. Labour Friends of Palestine and the Middle East (LFPME) has become one of the central organising hubs. Another is a WhatsApp group of about 30 MPs who share not only policy thoughts but also security advice, given the threats made to some Labour MPs especially in areas with lots of Muslim voters. Members of the WhatsApp group are now meeting frequently with David Lammy, the shadow foreign secretary, and with Starmer’s chief of staff, Sue Gray. Shabana Mahmood, the shadow justice secretary and Labour’s most senior Muslim MP, has become the de facto leader of this increasingly vocal caucus. However, tensions remain, including over recent comments by the shadow foreign minister Wayne David in which he told the Jewish Chronicle that Labour would only recognise Palestine after negotiations between Israel and Palestinians had begun. In a letter seen by the Guardian, seven backbench members of LFPME have written to Lammy arguing that the policy “effectively gives Israel a veto on Palestinian self-determination” and “will put recognition into cold storage for the foreseeable future”. In another sign of the Labour rifts being created by the war, the backbench MP Kate Osamor was suspended from the party on Sunday for referencing the “genocide” in Gaza in a post about Holocaust Memorial Day. A new poll carried out by UK in a Changing Europe demonstrates the risk for Labour, showing that nearly half of the country’s 2 million Muslim voters chose Labour at the last election. Given that a quarter of Muslims did not vote, two-thirds of those who did backed Labour. As long as Labour is 20 or more points ahead in the polls, Labour sources say these voters are unlikely to prevent the party from winning the election. But senior party figures are concerned that if the polls narrow, they could make the difference between victory and defeat in more than a dozen seats. Many of the Tory-held seats they are targeting, including Wycombe, Peterborough and Bury North, have Muslim populations well above 10%. The risk to Labour has been accentuated by the launch of a new grassroots group called The Muslim Vote, which is modelled along the lines of Operation Black Vote and aims to maximise turnout among British Muslims. TMV is organising voter drives and door-knocking campaigns in eight constituencies with the stated aim of “rewarding” MPs who vote for a ceasefire and “punishing” those who do not. A spokesperson for the group said: “It’s clear that Labour are taking the Muslim vote for granted and the Conservatives aren’t even interested in the Muslim vote. They have continuously devalued Muslim voters, the Labour strategy on Gaza has been to threaten to sack any shadow cabinet member who votes for a ceasefire.” However, officials are not only concerned about the Muslim vote. Some have also warned they risk losing votes in affluent, predominantly white parts of the country, such as Bournemouth, Bristol and Brighton, where many voters also feel strongly about the Palestinian cause. One Labour MP said: “We’re expecting to see middle-class Labour supporters sympathetic to the Gaza crisis to back the Greens because of their immediate ceasefire calls.” Another warned that younger voters in particular were being radicalised by the amount of footage they were seeing from Gaza on the social media platforms Instagram and TikTok. A party source said: “The discontent is much wider than the leadership realises. If we don’t get on top of this soon we are going to have trouble later this year.”