The Staggers 10 August 2016 The GMB endorses Owen Smith. What does it mean? Owen Smith's campaign has received an unexpected boost. Photo: Getty Sign UpGet the New Statesman's Morning Call email. Sign-up In a contest devoid of shocks, the GMB’s endorsement of Owen Smith is the closest to a surprise in a Labour leadership race that otherwise looks like a procession for Jeremy Corbyn. Why does it matter? Because unlike Usdaw, Community and the Musicians’ Union (which endorsed Smith) or the TSSA, Aslef or Unite (which have endorsed Corbyn) they did so following a “consultative ballot” of members, and the result is a 20-point victory for Owen Smith, with 60 to 40 per cent. For Labour’s Corbynsceptics, who have faced a series of setbacks, it represents a shot in the arm. If – and it’s a big “if” – GMB affiliates turn out in large numbers, then that would easily overwhelm Corbyn’s lead among ordinary party members. It will also bolster the argument made by Smith’s campaign that the balance of £25 supporters is far less pro-Corbyn than is commonly supposed. It also represents an endorsement of the series of fiercely-contended polls of trade union members, commissioned by Ian Warren, who worked for Labour under Ed Miliband, showed support for Corbyn slumping among trade unionists. Trade union affiliates can vote without a fee in the Labour leadership race, representing a big source of pro-Smith votes, or at least the theory runs. Is the spring in the Corbynsceptic step justified? Well, very few trade union affiliates voted in the last leadership election, despite a well-funded effort by Organise Consulting to sign up trade unionists on behalf of Unite. There is little evidence that pattern will be broken this time – so anyone hoping for an inrush of pro-Smith trade unionists is likely to be disappointed. The sole YouGov poll of the race so far showed Corbyn winning by 20 points among Labour members, and that pattern is broadly supported by his success in securing nominations from constituency Labour parties. It looks unlikely that enough trade unionists will vote to overcome Corbyn’s advantages among members. It’s also worth noting that as ever, there are complaints about process. In Labour politics – small and large “L” alike – the hand that controls the maillist tends to control the world. It may be that the GMB’s members vote very differently when ballots are issues. What is likely to be more important is that it will provide Tim Roache, the GMB’s General Secretary and a Corbynsceptic himself, the cover to be more critical of Jeremy Corbyn over the coming months, and allow the GMB’s representatives on the NEC to vote against Corbyn more freely, if – as still looks likely – he is re-elected. Among other things, that makes Tom Watson’s plan to seek a rule change to restore Labour’s electoral college look more likely to succeed, and Team Corbyn’s hopes of removing Iain McNicol will be thrown into doubt. So while it feels unlikely that GMB’s endorsement will change the outcome of the battle, it may represent a decisive shift in the longer struggle for supremacy. › The NS Podcast #167: Mayoral special Stephen Bush is political editor of the New Statesman. His daily briefing, Morning Call, provides a quick and essential guide to domestic and global politics. He also co-hosts the New Statesman podcast. Subscribe For more great writing from our award-winning journalists subscribe for just £1 per month!