The biggest reform to hit Welsh schools in a generation has caused widespread confusion and is likely to fail, a survey of heads and teachers suggests.
Half of heads do not believe the school effectiveness framework (SEF), which is being rolled out across Wales, will deliver improved standards, according to the poll by the National Association of Head Teachers Cymru.
More than half of classroom teachers surveyed said they did not know what SEF was actually about.
The initiative was designed to boost Wales' educational performance, with families of schools and teachers across local authority boundaries sharing good teaching practice and improving on their weak areas. But three- quarters of teachers suspect SEF is an indirect way of cutting frontline services, according to the poll.
For several months, leading academics and teaching union leaders have been expressing similar concerns in private - that SEF has lost direction and the Assembly government has lost the initiative.
But when questioned by TES Cymru, education minister Leighton Andrews angrily dismissed the concerns as "complete and utter tosh" and said he would not put up with "whingeing".
Although the vast majority of heads surveyed think SEF is a good idea, more than 90 per cent believe mounting paperwork and extra travel and cover costs will be major barriers to putting it into practice.
One secondary head revealed that he had been sent 75 pages of key stage 3 pupil attainment data as part of the SEF this week, with KS4 and KS5 data sets to follow.
Iwan Guy, NAHT Cymru's acting director, said data overload of this type was "self-defeating".
Tegwen Ellis, headteacher of Ysgol Cynwyd Sant in Maesteg, Bridgend, said: "We were keen to pilot SEF - it was exciting and looked good on paper - but the support just wasn't there. We found SEF too difficult to implement in practice."
Supporters urged doubting colleagues to make SEF work, blaming communication problems for gloomy predictions.
Dr Chris Howard, former NAHT president and head of Lewis School, Pengam, Caerphilly, said: "There has to be a `can-do attitude' when austerity hits, and SEF is the best chance we have now. Local authorities must allow schools to do this and not see it as a threat."
Mr Guy said: "The initial enthusiasm and positive attitude for SEF has diminished. There is a feeling that SEF is something being done to schools rather than with them."
Speaking to TES Cymru, Mr Andrews said: "It's complete and utter tosh. I don't believe there's genuine concern out there. I think there's clear understanding. I'm not going to put up with any whingeing about it."
An Assembly government spokesman said there had been great "buy-in" to SEF and all local authorities have given a "clear commitment" to take it forward.
The spokesman added: "It has received significant support from the professional learning community not just here in Wales but also internationally. The minister has determined there will be a simple focus on literacy, numeracy and breaking the link between poverty and attainment."
More than 860 practitioners recently attended four events across Wales to inform those delivering SEF about its priorities and how best they can be delivered at classroom level.