The main steel union ISTC, in partnership with other TUC affiliates, will begin the campaign today with Johnson Matthey of north London and Canadian company Co-Steel which has a plant at Sheerness in Kent.
Both companies have withdrawn recognition from unions - the only organisations in the steel and metals sector to do so - but both may have to reverse the decision should Labour be elected. Unions in other parts of industry are expected to adopt a similar strategy.
Tony Blair has pledged that businesses will be legally obliged to deal with unions where a majority of employees in a workplace vote for it. The ISTC claims majority membership at both plants. Albion Pressed Metals, part of the German Thyssens group, which has never recognised unions, will be next on the hit list.
Union officials at ISTC argue that the election of a Labour government in the spring is inevitable and that it makes sense for companies to deal with unions voluntarily rather be forced to do so after potentially acrimonious litigation. Union leaders argue that a similar approach was successfully adopted over European Works Councils where scores of companies established consultative procedures before a European directive was introduced on 22 September.