The School Standards Minister, David Miliband, has faced hostile questioning and shouts of "shame" from teachers unconvinced by assurances about school budget shortages.
David Miliband attempted to persuade a sceptical audience
The minister was speaking in Blackpool at the annual conference of the Association of Teachers and Lecturers, where he argued that local authorities were failing to pass on increases in school funding.
Mr Miliband said £500m intended for schools this year was still being held back by councils.
But his rejection that many schools faced budget cuts prompted cries of "shame", from members of this traditionally-moderate teachers' union.
This year, education ministers are refusing to attend the "bear-pit" of the National Union of Teachers' conference next week.
But even this more restrained gathering made clear to Mr Miliband that there are deep-seated concerns about funding.
According to speakers at the conference, many schools face budget shortfalls which could lead to staff redundancies.
"The present settlement is going to provoke an unprecedented crisis in many of our schools," said the union's acting joint general secretary, Gerald Imison.
There were claims that Somerset could lay off 40 teachers and support staff, Cornwall 32 staff and Stoke could lose 63 posts, as a result of budgets failing to meet increased costs such as higher teachers' salaries, rising national insurance and pensions contributions.
But Mr Miliband reiterated the government's commitment to increased spending for schools, up by £2.6bn this year - and a total increase of £6bn over three years.
And he sent the message that if there was a problem with funding it was at local and not national levels.
Although not offering any assurances that there would not be any teacher redundancies, he said that such fears were premature until all funds intended for schools had been delivered.
Mr Miliband's speech, despite the sceptical tone of questions from delegates, had been designed to reinforce the government's commitment to a partnership with "constructive" unions such as the ATL.
"There is a choice for trade unions: engage and be influential, or stand on the sidelines, enjoy shouting slogans, but be marginal," said the minister, in a side-swipe at more militant teachers' unions.
The wide-ranging speech again highlighted that the future of GCSEs as a full-scale qualification could be uncertain, as he pointed to the difficulties of having exams at each year between 16 and 18.
"High stakes tests every year are unusual," he said.
And he emphasised the importance of recognising the recent achievements of schools in England, including the recent international recognition of primary schools as among the best in the developed world for literacy.
The Conservative education spokesperson, Damian Green, said that David Miliband's speech "shows an alarming degree of complacency".
"He is trying to shift the blame for the schools funding crisis onto local education authorities when the real culprit is the government."