Which, if any, union will win the battle for members in the construction industry? Julian Birch and Grant Prior report.Within the past two weeks, two convenor stewards on major sites have defected from construction union UCATT to the electricians' union EETPU.The departures of Harry Cowap at Ludgate in London and John McGuinness at Strangeways in Manchester are the most high profile successes for the electricians in the private sector since they launched a new construction section staffed by defecting UCATT officials.While their success in signing up members has caused some consternation within UCATT and focused attention on the policies of the two contractors concerned, Bovis and Trafalgar House, nobody is pretending that it marks a definite breakthrough for the electricians or defeat for the mainstream unions.Mr Cowap and Mr McGuinness were closely associated with Jack Henry and Jack Rogers, two of the members of the UCATT executive council who were defeated in elections which shifted control of the union to the Left earlier this year.George Brumwell, UCATT EC member and now the favourite to take over as general secretary, argues: 'They're looking for one or two flashes in the pans on prestige contracts'.Mr Brumwell, who has been acting regional secretary in Yorkshire since the previous incumbent, Paul Corby, and two other regional officials went across, argues that the EETPU is 'like a snowball, they're melting away'.It is the private sector, and especially the chances of recognition from the Building Employers Confederation which are the keys to the EETPU'S prospects in mainstream construction trades.For it would be a mistake to believe that its new construction section was formed just to poach members from the mainstream unions or that the full time officials who have come across were motivated solely by higher salaries or antipathy towards the new leadership of UCATT.Construction has always represented one of the biggest potential recruiting grounds for unions. Only a small minority of the workforce is unionised, but so far no union has been able to find the right formula to attract hundreds of thousands of self-employed workers.But the EETPU faces a chicken and egg situation. Until it has the members it cannot push for recognition, and until it has the recognition it will find it difficult to get the members.At the moment it claims about 7,000 members, and according to the scenario painted by one sympathetic industrial relations officer, it must pass the psychological 10,000 mark before coming back to the EEC.This would enable the BEC to argue that the EETPU has as many members in construction trades as the other signatories to the building agreement, timber union FTAT and general union GMB, and so grant recognition.But things could prove to be more complicated than that. While three of the big contractors, Bovis, Costain and AMEC, appear to be adopting a sympathetic line towards the EETPU, two others, Laing and Mowlem, seem to be stayingwith UCATT.The internal politics of the BEC, notably on whether the national contractors should split off and have their own agreement with the unions, may also come into play.For Paul Corby, now head of the EETPU's construction building trades section, the result is a frustrating wait before he can push for some of his ideas to be implemented.