School leaders are overwhelming opposed to current Government education policies and future plans, a survey of senior staff has found.
Some 93% of head teachers, their deputies and assistants polled by the National Union of Teachers (NUT) agreed it was "inappropriate" for the Government to enforce the academisation of 17,000 primary schools within the next six years, stripping them from local authority control.
Three-quarters (74%) said cuts to local children and family service funding were increasing pressure on teachers, while seven in 10 (70%) said their school's funding situation next year will negatively affect educational standards.
Some reckon cuts in Government funding will reduce their school's budget by 10% in real terms.
The survey showed 98% of school leaders are concerned about workload and the work-life balance.
Christine Blower, NUT general secretary, said: "These findings are bleak and reveal bitter distrust from school leavers of the direction of travel for education policy in England.
"There are logical reasons why half of these school leaders say that they cannot go on and they are thinking of leaving.
"The Government has the wrong priorities. The strategy of cuts, teacher shortages and far-reaching, chaotic curriculum and assessment changes simply isn't working."
The NUT is holding its annual conference in Brighton until Tuesday.
A Department for Education spokesman said: "The fact that almost 70% of all open academies have voluntarily become one suggests the concerns raised by those polled by the NUT are not shared more widely across the country.
"On funding, we are protecting the schools budget in real terms and making funding fairer by introducing a new national funding formula so that areas with highest need attract the most funding.
"We also know unnecessary workload is one of the biggest frustrations for teachers and have done more than ever to tackle this by launching the reports yesterday of the three review groups to address the key concerns raised through the Workload Challenge.
"Rather than simply opposing our reforms, which have already seen 1.4 million more children in good or outstanding schools than in 2010, the NUT would do teachers and pupils a much greater service by engaging constructively with them."