A radical shake-up of pay and conditions for school support staff is foundering because local authorities are dragging their feet and some heads are refusing to implement the results, local government union Unison said at its annual conference.
And the Government was warned that its reform agenda - which increasingly relies on classroom assistants and office staff to relieve the pressure on teachers - would be undermined if ministers failed to deliver the cash to back it up.
Support staff were given the backing of the Local Government Association, which this week launched a working group to examine their pay and conditions, which remain among the worst in the public sector. Many are employed only term-by-term and paid nothing during the summer holidays. And contracts can vary even within a school.
While Government reforms have placed new demands on them, their pay has fallen even further behind teachers. Unison says average pay for teaching assistants has fallen from 45 per cent of teachers' pay to 38 per cent since 1994.
They should have benefited from "single status", the union agreement which put manual and white collar council staff on the same contract. But school staff have been among the last to be regraded amid fears that it would lead to a huge increase in LEA payrolls.
Kirklees in West Yorkshire is one of the few authorities to have agreed a complete new pay structure for its school staff It should mean pay rises of up to pound;300 a month for some. But Unison education steward and special school teaching assistant Julie Thompson said barely half of schools had implemented it in full.
"Headteachers and governors are saying to support staff: choose which one of you is going to lose your job - there's six of you and we can only afford five.
"Administrative staff are handling multi-million pound budgets, but the senior management team don't think they should pay them bursers' wages because they would be getting more than teachers."
Labour pledged an extra 20,000 support staff over the next five years in its general election campaign and last month announced training courses for 1,000 bursars. It believes they hold the key to relieving the bureaucratic burden on teachers in the face of union threats of industrial action.
Both Unison and the LGA this week called for ring-fenced cash for those staff, saying that without it schools would not be able to afford to recruit the high-quality support they needed. The union's conference in Brighton voted for a campaign for better funding.
Christine McAnea, Unison's head of education, said: "In some jobs you can get more money working on the till in Safeway, and most service sector jobs are totally flexible about hours. Schools may still be able to recruit staff but will they be able to recruit the right calibre?
"They want to recruit more men, but the level of pay puts them off."
Qamp;As on teaching assistants, 'Your Subject', www.tes.co.uk