But the Independent Education Union is not the only body stepping up its lobbying efforts amid claims of uncertainty about non-government school budgets next year.

Fairfax Media has obtained a letter in which the Catholic Education Commission NSW urges diocesan directors and principals to seek immediate meetings with local federal MPs to query the shifting funding figures.

It suggests grilling MPs on when the financial impact on each school will be known and what guarantees the government can give that the full funding will ever actually be found.

In Wednesday's letter, the chair of the Catholic Education Commission NSW, Bishop Anthony Fisher, warns the issue could remain ''a political football for several more months''.

It came as an IEU survey found just 7 per cent of members felt their school would be better off under the new funding model next year, while 35 per cent thought they would be worse off and 21 per cent about the same.

But given the frenzied political environment of claim and counter-claim, more than one in three members surveyed - 36 per cent - did not know the impact of the plans.

The IEU, which surveyed about 1600 teachers at Catholic and independent schools in NSW, is worried about the slow start to extra funding outlined in last week's federal budget.

While $2.8 billion in extra federal spending is earmarked over the next four years, the budget also includes $2.1 billion in savings from redirecting national partnership funding. Even more is saved when higher education cuts are taken into account.

Both the government and opposition have accused each other of planning to send school funding backwards.

The IEU is calling on its members to spend the next week lobbying Labor MPs for clear local details of the needs-based reforms stemming from the review by businessman David Gonski.

IEU federal secretary Chris Watt said his union had become frustrated at its inability to provide advice to members who were asking what the reforms meant for them.

''The problem with the major injections of cash is they do seem to be in three parliaments' time and in the meantime we have to deal with these issues of workload, wages and job security before we get to the golden era,'' Mr Watt said.

Separately, the strongly supportive Australian Education Union - representing teachers in public schools - called on the Coalition to respect the government's $5 billion six-year agreement with NSW and to honour similar deals other states may strike.

"It would be appalling if the Coalition proves to be putting electoral politics ahead of every Australian child's education by seeking to wreck late-stage negotiations underway between the federal and state and territory governments,'' AEU federal president Angelo Gavrielatos said.

Mr Gavrielatos seized on opposition education spokesman Christopher Pyne's admission, in a letter to premiers, that the Gonski review provided ''a road map'' to improve student education outcomes.

Mr Pyne said a Coalition government would extend the current system and keep national partnership funding while negotiating a new co-operative agreement.

Visiting Auburn West Public School in Sydney, Prime Minister Julia Gillard said: ''Christopher Pyne is thrashing around with every distraction he can think of because he doesn't want to stand in front of a television camera and say he and Mr Abbott stand for schools missing out on $16.2 billion.''

with Ilya Gridneff