Keir Starmer faces battles over the two-child benefit cap and other flashpoints at a key Labour policy gathering this weekend where trade union delegates will cite new evidence of the mounting cost of living crisis facing their members. Discontent at all levels of the party over his resistance to pledging to scrap the cap if Labour wins power forms the backdrop to potentially stormy negotiations behind closed doors at the National Policy Forum (NPF). About 200 representatives from all major parts of Labour – including constituency parties, affiliated trade unions, socialist societies and MPs – will meet over two days in Nottingham as part of the process of shaping the party’s policy agenda. The left of the party, in the form of Momentum and MPs including John McDonnell, is petitioning delegates to push for the adoption of “bold” policies such as scrapping the two-child benefit cap and introducing free school meals. Significant challenges are also likely to come from trade unions, who traditionally have preferred to take on the leadership in private. “Nobody expects Labour to get rid of the two-child cap on the first day, but if you are serious about lifting families out of poverty then there really has to be a signal sent out that this is something which will be tackled,” said one union source, who said “robust” pressure for a change in Labour position has been applied. Another union, Usdaw, said its priorities at the NPF would be informed by new survey findings it was releasing on Friday showing how the cost of living crisis continued to have a devastating impact on low-paid workers. As many as 81.5% of the retail union’s members said they felt worse off now than they did 12 months ago, compared with 39% in 2021, the survey by the UK’s fifth-biggest trade union found. “Disturbingly, nearly three-quarters of Usdaw members said that their children are missing out because money is too tight,” said Paddy Lillis, Usdaw’s general secretary, who hailed Labour’s commitment to increasing statutory sick pay within the first 100 days of coming into government. Calls by the union for an immediate rise in the minimum wage to at least £12 an hour for all workers, as a step towards £15, are likely to find an echo in some amendments put forward to the NPF from the left. Among others heading to Nottingham will be Christina McAnea, the general secretary of Unison, who in a blogpost on the public service union’s website has argued for the abolition of the two-child cap. “Unison is clear that good political choices result in economic growth that’s shared fairly across everyone in society, and a dramatic reduction in the number of families who are forced to rely on support. But until that happens, critical safety nets for children must be put back in place. And all politicians should reject any policy that’s proven to impoverish families, and that clearly punishes innocent children,” wrote McAnea, who has been regarded as an ally of Starmer and whose election in 2021 was seen as a blow to the party’s left. In political horse-trading away from the glare of the media, shadow ministers will be involved in attempting to reach compromises with delegates who have put forward amendments. Aside from what may emerge from the NPF, a series of flagship Labour policy announcements such as plans to create a publicly owned power company called Great British Energy and to abolish the non-dom tax status have already been put forward by the Labour leadership in an 86-page draft policy document. A report that will emerge from the weekend will go before the Labour party conference in October. Some amendments that have not been withdrawn or subject to compromises will be put to conference if they get a 35% vote of all delegates at the NPF gathering. Beth Winter, an MP on the party’s left, said: “We’ll hear a lot about difficult decisions and tough choices in the coming days. If we are going to convince people that the Labour party is going to build a better Britain, we need to challenge this Westminster orthodoxy and build support for the bold policies that offer hope.”