Eamonn O’Kane will present a paper to the annual conference of the National Association of Schoolmasters Union of Women Teachers which argues that growing financial pressures could force teaching unions to merge. It says that all teaching unions need to consider closer co-operation to cut costs and maintain services on offer to members.

Mr O’Kane, NASUWT general secretary, will hope that the report will win over sceptics who threw out a motion backing unity at last year’s conference, his first as the union’s leader.

The report has the backing of the union’s national executive and sets out the options for change but stops short of calling for a merger. In addition to a formal merger, options include:

* sharing the costs of services to members with other unions;

* forming a federation of unions;

* agreeing to limit the recruitment of members to certain sections of the education service.

Opponents of unity within the union’s leadership have resisted pressure from Mr O’Kane to back it, and believe that delegates will reject the proposals.

The report argues that the complexity of employment law, combined with teachers’ workload, means that the union has increasingly to rely on professional staff to carry out casework.

Mr O’Kane said: “For all the unions there is a question of whether we can carry on as we are and maintain services in the medium to long term. I think that many of those opposed to merger might back the sharing of services if it benefits members.”

If the report wins the backing of delegates there will be a formal consultation with members, followed by a document setting out the leadership’s proposals within a year.