The government is facing renewed pressure from unions to change course over its decision to strip the winter fuel allowance from the bulk of pensioners, as a minister said she understood why many Labour MPs could struggle to back the policy. With as many as 50 backbenchers predicted to abstain or be absent when the policy is voted on in the Commons on Tuesday, union leaders reiterated their call for a U-turn as the Trades Union Congress (TUC) gathered for the start of its annual conference in Brighton. Paul Nowak, the TUC general secretary, said he had “real concerns about this decision” to remove the previously universal payment from all but the poorest pensioners, those who receive pension credit. “I don’t want any pensioner going into the winter worried about putting the heating up,” Nowak told Sky News, calling on Rachel Reeves, the chancellor, to find ways to mitigate the policy. “I hope that the chancellor will set out in the budget what she’s going to do to make sure those pensioners, not just those on pension and tax credit but those who aren’t well off by any means, do go into the winter confident that they can heat their homes and stay safe and comfortable,” he said. Sharon Graham, the general secretary of Unite, reiterated her union’s call for the decision to be reversed, and for efforts to plug what Reeves says is an unexpected £22bn deficit left by the last government to be focused instead on ideas like a wealth tax. Keir Starmer, who accepted on Sunday that the policy was “unpopular” but said he expected Labour MPs to back it in the Commons, “needs to do a U-turn”, Graham told BBC Radio 4’s Today programme. “Leadership is about choices, and he needs to be big enough and brave enough to do a U-turn on this choice,” she said. “It’s completely wrong. People do not understand how a Labour government has decided to pick the pocket of pensioners and at the same time leave the richest in our society totally untouched.” Few Labour MPs are expected to openly oppose the government in the vote, which was triggered by the Conservatives formally opposing the winter fuel payment plan, particularly after a mini-rebellion on another issue in July in which seven backbenchers were suspended from the party. However, dozens are believed to be considering abstaining or being absent, although rebels say the numbers in their ranks are very hard to predict. Diana Johnson, the policing minister, sent out to speak for the government on Monday morning, defended the policy – but also said she understood why many colleagues felt unable to back it. “I don’t think anybody wants to see this proposal around the winter fuel allowance brought in,” she told BBC One’s Breakfast programme. “But as the prime minister has said, we’re going to have to make some tough decisions. It’s a tough one, but it’s one that the chancellor obviously feels we need to make.” Johnson said she was “not surprised by the amount of concern that there is about this” among colleagues, adding: “I understand, for many MPs, this is a really hard decision. I myself have had lots of constituents contact me so I know how difficult this is.”