UK 19 February 2019 What exactly do Tory rebels want on the backstop? Ministers want a codicil, but the ERG leadership is making clear that nothing less than its removal will do. Just how many MPs agree with their analysis will determine how easily May's deal can pass. Getty Sign UpGet the New Statesman's Morning Call email. Sign-up Labour’s disunity is the story of an otherwise quiet week at Westminster: this, after all, was supposed to be recess. But the divisions on the Conservative benches are looking increasingly intractable too. Raising hackles in the European Research Group: reports that Theresa May has told Cabinet that the so-called Malthouse Compromise – a Brexiteer-endorsed plan to denude the withdrawal agreement of the Irish backstop and replace it with technological solutions – is not something she will pursue. Though May had never given that specific plan her explicit endorsement, hardline Eurosceptics believe its adoption as government policy was the price for their support in last month’s Brexit vote, which the prime minister won on the basis that she would replace the backstop with alternative arrangements. They also insist that gutting the divorce treaty of the insurance policy entirely – rather than adding a time limit or unilateral exit clause – is the only way to build a sustainable majority of Conservative and DUP MPs. That plan, however, was always bound to combust upon contact with the political reality of the situation in Brussels and Dublin. The Northern Ireland protocol of the withdrawal agreement is going nowhere, and the best the UK might hope for is additional legal assurances that the backstop is temporary, most likely in the form of a codicil to the treaty. This could offer the change to the legal effect of the withdrawal agreement that the DUP leadership, from whom many Tory MPs are taking their cues, has been careful to demand rather than wholesale change to its text. Securing a compromise of that variety has been the focus of Steve Barclay and Geoffrey Cox’s trip to Brussels this week. Should the result be a form of words or legal accord that convinces the Attorney General that the UK would not be locked into the backstop’s customs and regulatory provisions indefinitely, then the government can count on the DUP’s votes and, if last week’s Brexit vote is anything to go by, just under half of the 118 Conservative MPs who opposed the withdrawal agreement at the first time of asking. But as far as the more doctrinaire end of the ERG is concerned, the sort of compromise that is in the offing will not be enough. Steve Baker, its deputy chairman and effective chief whip, has dubbed the plan for a codicil “Cox’s codpiece”. The chances of a negotiated settlement passing the Commons depend to a large extent on how many MPs agree with his analysis. A big chunk of those 118 Tory rebels is not particularly dogmatic and will follow whatever course is set by Cox and the DUP. Other prominent Eurosceptics, like Boris Johnson, have also suggested they will accept something less than the wholesale change to the treaty they initially demanded. Yet these shifts will mean very little if the 67 ERG MPs who rebelled last week do not accept a compromise. Just how many prove irreconcilable will test two pervasive, but in this case potentially mutually exclusive, tenets of parliamentary received wisdom. The first is that Baker has a reliable and biddable bloc of Tory backbenchers at his beck and call. The second is that most Conservative Eurosceptics will, when push comes to shove, take whatever line the DUP does on the backstop. That second assumption has already been tested by their divergent votes last week. If it is comprehensively disproven in the coming days, then Theresa May will need many more Labour votes to pass a withdrawal agreement than she has hitherto reckoned. › The Honda closure is not about Brexit – but it still reflects the weakness of the British economy Patrick Maguire was political correspondent at the New Statesman. Subscribe For daily analysis & more political coverage from Westminster and beyond subscribe for just £1 per month!