The SNP has also urged Cathy Jamieson, Education Minister, to accept there will have to be a split on National Qualifications between colleges and schools if there is no progress on cutting burdens from the latest assessment support group.
The union's executive council, which meets today (Friday), is being advised to support a pound;26,000 indicative survey by pollsters from System Three. It will be the first time the union has conducted such a sampling exercise and it is pressing for a high response.
There are likely to be four questions about assessment with the final one on a possible boycott of compulsory unit tests from Intermediate level upwards. The other three questions are more open and seek views about National Qualifications and the role of assessment.
The survey follows last week's move by ministers to set up an assessment support group, but union leaders believe their initiative will prove more significant.
They are keen to face down critics on the left, who in June won key victories at the union's annual conference in Dundee, forcing today's special executive meeting. Mainline representatives insisted there was no "substantial fire in the belly" among members about their strategy and no clear classroom consensus about the best way forward.
But the critics won the day by tapping continuing discontent about unit assessments and the apparent lack of action. The wider membership will now pass judgment.
Mike Russell, the SNP's shadow education minister, has called for the many objections from teachers about the post-16 system to be resolved by adopting a more radical approach. "I want ministers to realise that simplification is necessary to get teachers to do their job. It's not just a question of bureaucracy. If it is impossible to square the circle between the demands of schools and colleges, then find a structural way to do it, don't keep trying to do it within the same structure. I think that's one of the difficulties they have got."
He welcomed the new group but doubted ministers' commitment. "If the root of the problem is that they can't square the circle between further education and school requirements, cut the Gordian knot," Mr Russell said.