Leaders of Britain's largest headteachers' union have caved in to demands from members to hold a special conference to debate withdrawing from the school workforce deal.
The National Association of Head Teachers' council decided last week to hold an extraordinary general meeting in the face of requests from rebel branches, angry about a lack of funding for the agreement.
It bowed to the inevitable as the union prepared to receive the required 20 per cent of members from three of the association's 12 branches needed to trigger the meeting.
The decision represents a major setback for the council, which voted by 29 to 13 in November to stay in the agreement, and to David Hart, the general secretary.
He has said that pulling out of the deal would be catastrophic and that holding the special meeting would be a "recipe for splitting the NAHT asunder".
The meeting is likely to be held in London, in March, when most schools should have received their budgets.
It will be smaller than the annual NAHT conference, with around 150 to 200 members expected from every local branch, association and region, as well as the national council.
Rona Tutt, NAHT president, said: "I understand some people are very, very angry because they feel we have signed up to something they feel the Government has not delivered on."
She added: "I think it is fair to say there will be a lively debate."
Some feel the debate could have an impact on the NAHT leadership election which is also in March, with David Hawker, the council's candidate, suffering from the fall out.
His challenger Mick Brookes, a Nottinghamshire junior school head and former NAHT president, was nominated by the South-west and North-west, key rebel regions.
And although both candidates are against withdrawing from the deal, there is a feeling among some activists that Mr Brookes could benefit from a desire to "give council a kicking".
Mr Hart said he thought that by taking the initiative and convening the meeting before branches did, the NAHT could ensure a more positive motion was considered.
But he conceded: "At the end of the day, the key issue is whether the NAHT stays in or out."
That has been the case almost since the deal - which guarantees teachers 10 per cent planning, preparation and assessment time from September 2005 - was signed in January 2003.
The NAHT has continually threatened withdrawal over funding. A stormy debate at last year's annual conference saw the union's members, most of whom are primary heads, defy Mr Hart and set an end of 2004 deadline for "clear, adequate and direct" funding for the deal.
Paul Woodward, the association's regional secretary for the South-west, said: "People are angry and frustrated. We want to make this work but if we are going to do it properly, it needs to be funded."