The Prime Minister is expected to tell the Cabinet tomorrow that he is determined to enforce stringent tests before a union can win recognition at the workplace.
In particular, he will reveal that the White Paper on "fairness at work", due to be published within weeks, will insist that employees' representatives have to win 40 per cent backing of the relevant workforce in a ballot, not just a simple majority of those voting.
The Confederation of British Industry originally argued for a 50 per cent threshold, but has subsequently accepted the 40 per cent figure.
In the teeth of opposition from some union leaders, John Monks, general secretary of the TUC, offered a compromise of 30 per cent.
Some leading trade unionists will reluctantly accept the Prime Minister's formula - given other employee-friendly elements of the White Paper - while others will be less gracious.
Bill Morris, general secretary of the Transport and General Workers' Union, yesterday suggested that there be a referendum on the White Paper among all 7 million union members.
While Mr Blair is anxious to agree with the CBI on an issue which has received the most public attention, he is expected to offer unions something in return.
More to trade unionists' liking is likely to be a decision on who will draw up the constituencies for ballots. Margaret Beckett, President of the Board of Trade, has told employees' leaders that the initiative will initially lie with unions.Reuse content