Starmer is facing a cocktail of dissent that is growing ever more potent

But for the Iran crisis, Labour’s first major policy announcement since the party’s calamitous defeat in the Gorton and Denton byelection would have been arguably the biggest political story of the week.Shabana Mahmood, the home secretary, pressed ahead with what is intended to be the party’s full-throated answer to the competition it faces from Reform UK as she declared an end to permanent refugee status and the removal of state support from some asylum seekers.It immediately put her on a collision course with many Labour backbenchers, but it also left the party’s soft-left majority, who had been pushing for a more progressive offering in recent weeks, asking: “Is that it?”The victory speech in Gorton and Denton by Hannah Spencer, the newly minted Green Party MP, contained the sort of lines that many on Labour’s backbenches yearn to hear their leader utter, or even nod towards. Hard-working people had become “sick of making other people rich” and now wondered what their toil would yield, said the young plumber.Yet while Keir Starmer’s troops expected at least some red meat this week from their party’s leadership to counter the Green challenge for economically squeezed traditional Labour voters, his instinctive response was to send a letter to MPs in which he repeated an attack line that sought to paint Zack Polanski’s party as extremist.Several at the parliamentary Labour Party meeting on Monday took issue with the letter’s message, and a senior minister shared their disappointment with the Guardian that Starmer had not responded to the loss of Gorton by talking about the cost of living.Without any progressive offer for Labour MPs, the prime minister now faces a mounting rebellion over Mahmood’s plans, which had been intended to at least cauterise the issue of immigration with the public and could create room to lean leftwards.Shabana Mahmood speaks at the Institute for Public Policy Research in Westminster on Thursday. Photograph: Stefan Rousseau/PAThe MPs’ revolt includes a letter organised by Tony Vaughan, the Labour MP for Folkestone and Hythe, who said it was signed by 100 colleagues who believed the proposals undermined the government’s commitment to integration and social cohesion.Another backbencher, Stella Creasy, used a Guardian article to set out a vision of what she described as “True Labour” – an alternative path for the party to the Blue Labour doctrine associated with Morgan McSweeney, Starmer’s recently departed chief of staff.Behind the scenes, Labour MPs were openly divided after being told by party chiefs to share Mahmood’s migration proposals. “Absolutely not,” responded one, with others echoing the sentiment, while others defended the plans.Those Labour MPs hoping that McSweeney’s departure last month might have freed their leader from what some had come to view as a Rasputin-like influence would have been disappointed by Starmer’s laudatory speech at his former aide’s leaving do in a Westminster pub on Wednesday night.Since his departure, Labour MPs had hoped they might have more say in policy formulation. No 10 has been working to improve relations with backbenchers, with invites to Chequers and more conversations with aides.But many feel it is not enough, citing what they said was limited opportunity for input into Mahmood’s proposals. Others feel the same about next week’s plans for courts reform.This all makes for a heady cocktail of dissent for the prime minister as the clock ticks down to local elections in May, when an expected Labour electoral bloodbath – some of it at the hands of the Greens – could be a perilous moment for his leadership.Even in a week when Starmer was focused on the Middle East, it will not have escaped his attention that Angela Rayner and Andy Burnham – two potential soft-left leadership rivals – were making eye-catching speeches. Labour MPs will also have been reminded of their availability.