The new curriculum is due to be implemented in all schools by August
The controversial new school curriculum needs to be either "fixed or ditched", a teaching union has warned the Scottish government.
The call was made by the president of the Scottish Secondary Teachers' Association at its annual congress.
Delegates backed a motion calling for industrial action if key improvements were not put in place.
The Scottish government said it would not be "diverted" from fully implementing the curriculum by August.
Peter Wright, the president of the Scottish Secondary Teachers' Association (SSTA), told Friday's congress in Peebles that the new Curriculum for Excellence (CfE) was "deeply flawed" and not yet fit to be fully rolled out in schools.
He said there needed to be dialogue with Education Secretary Mike Russell, and said the union had ideas for how the problems with the curriculum could be fixed.
Mr Wright said: "We know why secondary teachers are not fully behind CfE. It's because much of it is mince.
"CfE is, in a number of ways, a deeply-flawed programme which is not yet fit to be rolled out fully in secondary schools. But our members have told us what the problems are and we have suggestions about how they might be addressed."
The alternative to this, Mr Wright said, was that CfE be abandoned altogether in secondary schools, the consequences of which would be "serious but by no means unthinkable".
"In other words, with regard to Curriculum for Excellence, the message from the SSTA is: 'Mr Russell: fix it or ditch it'."
Mr Russell last month announced the new curriculum would be brought into secondary schools across Scotland in August.
The changes, already in place in primary schools, are designed to give teachers more freedom and make lessons less prescriptive.
But a survey of SSTA members found that 88% felt they needed additional resources to implement the new curriculum while 90% said the main problem was lack of assessment materials.
On Friday, delegates passed a motion backing a ballot on industrial action if "satisfactory progress" was not made with ministers by June.
They want "clear and unequivocal" information on curriculum structures, a list of the core skills to be taught for every subject area and working groups to develop core material.
General secretary Ann Ballinger said the proposed action would be "short of a strike" - but could see members working to contract.
Mr Russell said: "Let me be absolutely clear, Curriculum for Excellence is here to stay and it will be fully rolled out in secondary schools this August.
"I have based my decision on the unanimous advice given to me by the experts on the management board, of which the SSTA is a member and therefore voted for this decision.
"The board, which the SSTA has been a member of since 2008, has unanimously agreed each decision and that's why it is disappointing that the SSTA are now on the verge of turning their back on progress and balloting for industrial action."
Mr Russell said he was "fully committed" to continuing to discuss "real and genuine concerns" with unions.
"However, complaints and demands that show a deliberate misinterpretation of the very heart and principles of the new curriculum will not find any sympathy with me," he warned.
Mr Russell added: "I will continue to listen and work with teaching unions, but I will not be diverted, or allow the improvements of learning and teaching to be diverted, by those who are simply opposed to change."
Last week Mr Russell confirmed experts were producing simplified versions of key documents for the new curriculum.
New material will also be published, highlighting examples of good practice in key areas such as literacy and numeracy.