Labour’s biggest union backer has warned it may divert election funding earmarked for the party, amid claims that Keir Starmer is diluting plans to overhaul workers’ rights. In an interview with the Observer, Unite’s general secretary, Sharon Graham, said the Labour leader risked “limping into Downing Street” if he backed down in the face of intense lobbying from businesses. She warned that any rowing back or delay represented a “red line” for her and her members, adding she was seeking reassurances from Labour’s leaders. She also suggested that, with the election just months away, she would also consider using potential election funds to instead back a grassroots campaign that would lobby Labour MPs to stand by their pledges to workers. “When I went to our union’s rules conference last year, the thing I spoke about the most, as to why it was important for us to continue to back Labour, was the new deal for working people,” said Graham. “I’ve been really clear that I’m not interested in the factional politics in Labour, but I am interested in what goes on for workers. “We’ve got £29m in our political fund,” she said. “Of course, normally my conversations with Labour would be around policy, but also around how we can assist. Now we’re looking to see whether we have to spend some of this on trying to get them into the right place, campaigning in constituencies and making sure that they understand this is a really important thing. It’s not as simple a discussion as we thought it was going to be.” It comes after suspicions on the left that Starmer is watering down some of the key elements of the so-called “new deal for working people”, which was first announced by his deputy, Angela Rayner. It has since become a central campaigning issue for Labour in Scotland, which could be crucial in delivering the party a majority. Details of the latest version of the plan are set to be revealed soon. Many of the policies are to be the subject of consultations, which some fear will see them diluted or delayed. A pledge to give workers basic job protection from their first day of employment is expected to allow employers to use reasonable probationary periods for new staff. A vow to ban zero-hours contracts is expected to be changed to allow some workers to keep the status – but this has raised concerns that they may be forced to do so by pressure from their bosses. Unite was the only Labour-affiliated union not to approve changes to the programme when they were discussed during a party policy meeting last summer, because Graham feared it was being diluted by stealth. She said she was now being proved right. She said that a change in the party’s wording to ban “exploitative” zero-hours contracts, rather than the wider practice, was a worrying move that could create a power imbalance between bosses and their staff. “Obviously, we want a Labour government, I want a Labour government, the country needs a Labour government,” she said. “But there is a real difference between limping into Downing Street or being carried on workers’ shoulders. “This is not an issue about cost. This is an issue where they have been effectively moved by the business lobby, there’s no doubt about that. For me, it is a red line. I’m going to be meeting a number of Labour figures, including reaching out to Keir and having a conversation. I’m a negotiator. I know what changes of wording mean.” Other union leaders are currently backing Starmer over the plan and party officials insist the current process is simply exploring ways to translate the headline policies into a workable programme that weeds out unfair practices. Labour said: “The new deal will be a core part of Labour’s offer and we will be campaigning on this ahead of the general election. Labour’s new deal for working people was agreed at the party’s national policy forum last summer, building upon our green paper. Our commitments to bring forward legislation to parliament within 100 days to deliver the new deal and to consult widely on implementation have not changed.”