The Staggers 1 May 2013 Unite set to grow in strength as it begins merger talks with TSSA Len McCluskey's union enters negotiations on a formal merger with the Transport Salaried Staffs’ Association and more could follow. Sign UpGet the New Statesman's Morning Call email. Sign-up Labour Day brings notable news from the trade union movement. Unite and the Transport Salaried Staffs’ Association (TSSA) have announced that they have begun merger talks to form the UK's "first-ever cross-transport union". If successful, the TSSA, which has 23,000 members to Unite's 1.5 million, could become a new section of Unite by February or March next year. The TSSA was previously in merger talks with the RMT but according to Union News, "failed to resolve differences over the TSSA’s continued Labour Party affiliation and RMT’s backing for non-Labour candidates in parliamentary elections. Unite itself was formed in 2007 through a merger of Amicus and the Transport and General Workers' Union and when I interviewed him last week, Unite general secretary Len McCluskey told me that he was "open to a merger in principle with every union", describing it as part of Unite's "strategy for growth". I'm open to a merger in principle with every union, well, maybe there's one or two that I wouldn't, but I'm not going to name them. But yes, of course, we will talk to any union...I've already had discussions with several unions since becoming general secretarty and that is part of Unite's strategy for growth. After McCluskey's attack on the "Blairite" shadow cabinet ministers last week, the move has prompted concern among some on the Labour right, with one "Blairite" telling the Times: "It concentrates more power in [McCluskey’s] hands,” said one Blairite last night. “TSSA is a union with lots of middle class, professional workers who would not conform to Len McCluskey’s view of the world. They are the sort of people who vote for Labour, the Tories and the Lib Dems. "The attempts by McCluskey to drag us back to the dark ages have been very disappointing." But most in Labour are far more troubled by the possibility of another merger, that between the PCS, led by Mark Serwotka (who blogged brilliantly for the NS earlier this week on welfare reform), and Unite. At their annual conference this month, PCS members will vote on whether to begin merger talks with Unite to form a super union of 1.75 million members. The prospect of Unite, Labour's biggest donor, combining forces with a union that is not affiliated to the party has concerned Labour MPs, who fear it could lead to a reduction in funding. Unite was responsible for 28 per cent of all donations to the party last year and has donated £8.4m since Ed Miliband became leader. When I spoke to McCluskey he refused to rule out the possibility of a full merger. The PCS have their conference in May and my understanding is they'll be discussing the whole question of the future of PCS, so I suspect what we all should do is wait for the outcome of that conference. From Unite's point of view, we are always engaged in discussions with sister unions about whether there's a legitimacy for us to work closer on the one hand or, indeed, merge together on the other hand. There's certainly no formal discussions taking place with PCS and I think we should just allow their democratic process to happen and we'll see what comes out of that and then Unite will react to it. Of the concerns expressed by some in Labour, he said: I’m open to a merger in principle with every union, maybe there’s one or two that I wouldn’t, but I’m not going to name them. But yes, of course, we will talk to any union. As I said, I’ve already had discussions with several unions since becoming general secretary and that is part of Unite’s strategy for growth. A Unite-PCS merger would be the most significant event in the trade union movement for years, so the the latter's conference will be worth following closely when it opens three weeks today. › The DWP's bogus psychometric tests are dystopian, but randomised trials aren't the problem Unite general secretary Len McCluskey. Photograph: Getty Images. George Eaton is senior online editor of the New Statesman. Subscribe For daily analysis & more political coverage from Westminster and beyond subscribe for just £1 per month!