Chris Mason: Labour still has a big persuasion job ahead

"I've not had as much quality time with my colleagues since the Brexit wars," a minister told me with a wry smile. A remark that gets to the heart of this benefits row within the Labour Party: this is a government with a big majority, that has already performed a big U-turn and yet is still involved in a big persuasion job. This is not meant to happen, one year into government, with a working majority of 165. The prime minister himself will be getting stuck into some persuading today, making the case that these changes are, as he sees it, not only in keeping with Labour values but essential to ensure the long-term stability of the welfare state. But if Monday's Commons statement from Work and Pensions Secretary Liz Kendall was intended to reassure Labour MPs, it is an open question as to whether it worked. "It turned a fair few colleagues off. I think it will get through, but it'll be close," said one backbencher. There has been plenty of talk of there being 40 to 50 Labour MPs who are opposed, but things remain fluid. Given the size of the working majority, rebels would need to amass around 80 of their colleagues to vote against the government to defeat them, everything else being equal. But a key factor could be how many choose to abstain in the vote on Tuesday evening. Incidentally, Prof Philip Cowley of Queen Mary University of London notes that the biggest backbench rebellion Sir Keir Starmer has suffered so far is 16. The largest rebellion in Tony Blair's first year in Downing Street was 47 and also on the welfare state - over lone parent benefit. The largest backbench rebellion for any governing party in 200 years was in 2003, over the Iraq war. At the heart of plenty of the concern over these benefits changes is what is being proposed for the Personal Independence Payment (Pip) at the end of next year. From November 2026, the plan is the eligibility criteria for the main disability benefit will be tightened. Some Labour MPs and ministers had hoped a review of Pip, conducted by Work and Pensions Minister Sir Stephen Timms and involving disabled people, would reassure colleagues the government's intentions were something they could back. But over and over again in the Commons concerns were raised that the timeframe of the review - itself due to report in the autumn of next year - would mean it would be too late to have an influence on the eligibility criteria for Pip beginning that November. And beneath that there is an underlying critique: that the reason the plans for late next year remain in place is because that way it makes it (a bit) easier for Chancellor Rachel Reeves' numbers to add up - and, to use the jargon, for the measures to be "scored" by the Office for Budget Responsibility when it produces its forecasts, which are so central to the government's management of the economy. For plenty of Labour MPs this is wrong-headed, topsy turvy and an increasingly hard-to-defend approach to government. But it is also worth emphasising, as it always is when there is a debate dominated by noisy people, that there are quieter Labour MPs, many keeping their heads down right now, who find this whole row gratuitous and fundamentally naive - and, they argue, it is Labour's duty to grapple with a spiralling benefits bill. And Sir Keir and Rachel Reeves have long argued that Labour being seen as credible custodians of the economy is the building block upon which everything else is constructed. The Chief Whip, Sir Alan Campbell, in charge of winning the vote for the prime minister, has issued a plea for unity - something that only happens when there isn't a surplus of it - and told Labour MPs they should "act as a team". The party, he said, would have to come back together after this difficult vote for them. MPs will debate the plans all over again later, and the vote is expected early this evening. And even if the government does win, that won't be the end of the matter. More arguments and votes are expected in the next few weeks.