Julia Gillard's signature Gonski school education package is the latest reform area to fall victim to the underperforming mining tax, with the Greens threatening to change a key element unless the tax is fixed.
Just days after tearing up the 2010 written agreement with Labor to form government, Greens leader Christine Milne will announce on Friday plans to amend the $6 billion Gonski enabling bill in the House of Representatives to ensure funding goes to the poorest schools first.
She will use a speech in Melbourne to build pressure on the government to fix the mining tax mess.
"With the government failing to fix the mining tax we are worried that there will not be enough money to fund the full implementation of Gonski, indeed there are likely to be other programs with long delays due to the resistance of the government to raise more revenue," her speech notes say.
"If this is the case, then the additional funds available must be prioritised to where they are needed and that means they must flow to our most disadvantaged public schools."
The government is committed to delivering the schools blueprint this year but needs the support of the national Parliament, the states, and the Catholic and independent schools sector.
Shell legislation is before the lower house but key details of the new funding model remain unspecified.
The current school funding formula expires at the end of 2013.
Along with its $8 billion-plus National Disability Insurance Scheme, the Gonski package forms the central core of Ms Gillard's re-election pitch this year.
But in a threat to the government's already tight timetable, Senator Milne will tell the Australian Education Union conference shortly after Ms Gillard also speaks that the collapse of mining tax revenue means the Gonski plan faces a potential lack of funds.
The Greens believe protections must therefore be built into the enabling legislation to ensure the poorest socio-economic status schools are helped first and cannot be dealt down in heated pre-election negotiations between the government and the wealthier private sector.
The Gonski model, which was delivered to the government in 2011, proposes to fund all schools on the same per-student basis, albeit with loadings to accommodate such special conditions as socio-economic disadvantage, and disability.
However, the opposition's Christopher Pyne has called for the changes to be delayed for 12 to 24 months by extending the current funding arrangements.
He says the September 14 election date means the chances of getting an agreement with the states and private school sector are becoming increasingly unlikely and he predicts the program will become "another major government fiasco".
That has angered the AEU, which says rolling the current formula on will cause public schools to slip further behind.
"Extending the current funding arrangements is not a credible policy position," AEU federal president Angelo Gavrielatos said.
"It means billions of dollars of cuts to public schools, including from schools in the most disadvantaged communities in the nation."
The Greens also fear the government will come under acute pressure from the independent sector to increase assistance to private schools and will "wilt" as it did under the political pressure from miners leading up to the last election.
The surprise move follows another Greens' move revealed exclusively in Fairfax Media on Thursday to join the Coalition to block a $1billion jobs and innovation package funded by cutting research and development tax breaks for the biggest companies, unless the Minerals Resource Rent Tax is toughened.
The Greens believe they were duped into backing the MRRT in 2010 on the understanding it would raise nearly $10billion in its first four years and $2billion its first 12 months.
It has collected only $126million in its first six months even though billions in new spending for tax breaks on superannuation contributions and small businesses have been tied to its revenue.
Senator Milne said the MRRT’s failure was the result of the government caving in to the demands and public relations campaign of big miners.