Labour has lost more than a third of its support from teachers since the last election, an exclusive poll for The TES reveals today.
The survey of 700 teachers in England and Wales suggests that many will express their disillusionment with the Government at the ballot box later this year.
Most teachers felt the Prime Minister had failed to achieve his promise to increase support for schools and less than half of Labour voters rated the Government good or excellent.
However, Labour's education policies were more popular than those of any other party.
Yesterday Mr Blair and Ruth Kelly, Education Secretary, unveiled a new manifesto pledge, which puts parent power at the heart of their drive to win voters.
The poll suggests that teachers agree with several key Labour initiatives.
Two-thirds were in favour of specialist schools while a narrow majority backed the plans to expand foundation schools which control their staffing and admissions.
But two-thirds said they were opposed to privately-sponsored academies, which Labour has put at the heart of its plans to reform secondary education.
Asked who they had supported in the 2001 election, 43 per cent said Labour.
But only 29 per cent said they would vote for the party if an election were held tomorrow.
Support for the Conservatives fell from 10 to 9 per cent - disappointing for a party that has made protecting teachers from poor behaviour and malicious allegations key pledges. Backing for the Liberal Democrats has increased from 18 to 20 per cent. The Lib Dems had strongest support from teachers over 50 and were the most popular party with staff in independent schools.
Charles Kennedy, Liberal Democrat leader, said the Government had overburdened schools with testing and paperwork. "No one knows that better than teachers and the drop in support for Labour speaks volumes," he said.
Although staff are now paid significantly more than in 1997, teachers were divided over whether they felt better rewarded under Labour than under the Conservatives. Many classroom teachers felt there had been no improvement in pay but heads and deputies were more positive.
Pollsters FDS, who carried out the telephone survey in January, said better-paid teachers were clearly more likely to vote Labour. Labour won most support from heads and deputies, 30 to 39-year-olds and male teachers.
Four out of 10 teachers said they did not know which party had the best education policies. More than a third said they would either not vote or were undecided.
Schools where staff had a mix of views included Galliard primary in Enfield, the constituency of Stephen Twigg, school standards minister. John Maxwell, deputy head, said: "There was a lot of excitement among teachers about Labour coming to power, but the initiatives have been relentless. I voted Labour, but this time I'm not so sure."
But Deborah Lynch, a maths teacher at Harper Green school in Ruth Kelly's Bolton constituency, had no doubts. "I will be voting for Labour again as the others don't seem to have any education policies."