The Australian Greens will push for another inquiry into the mining tax to try to work out why the big resource giants aren't paying as much as expected.
Greens leader Christine Milne has challenged Labor to work with the minor party toward fixing the Minerals Resource Rent Tax (MRRT) before parliament breaks for winter at the end of June.
Labor MPs have ruled out redesigning the tax despite it only raising $126 million in its first six months of operation - well below the forecast $2 billion over 2012/13.
Senator Milne on Tuesday is expected to discuss the Greens agenda, such as calls for a MRRT inquiry, in an address to the National Press Club.
She said mining giants like Rio Tinto were "celebrating" the fact they hadn't paid any tax on their super profits.
"Meanwhile the pockets of single parents have been raided to make up the shortfall," Senator Milne told ABC Radio on Tuesday.
"What we need to do is get to the bottom of exactly how flawed this tax is, and what has to be done to fix it."
She said the Greens had the "courage" to stand up to the mining giants in an election year, but questioned whether any of the major parties had the mettle.