Key independent MP Tony Windsor says he is more than likely to support the government's proposed minerals resource rent tax (MRRT) when the bill enters parliament next week.
The minority government needs the support of four crossbenchers for the MRRT bills to pass through the House of Representatives.
Mr Windsor has said previously his support would be based on some funding from the MRRT to be used for independent assessments of the environmental impacts from coal seam gas (CSG) mining.
"It (the MRRT) is more likely to have my support," Mr Windsor told ABC radio on Friday.
"I don't know what the others will do or not, but we haven't concluded those discussions."
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He said the CSG assessment funding issue was his "line in the sand" in supporting the Labor government.
"If we don't do something about this, I am not going to support this particular tax unless some of the revenue from it goes to proper bio-regional assessment in these sensitivity areas," Mr Windsor said.
Mr Windsor, the member for the rural seat of New England in northern NSW, said his talks with the government had been about the process, not the money.
He said this was to ensure a combination of state and federal involvement with a revenue flow so the mechanisms would actually work.
Mr Windsor said he had talks with Prime Minister Julia Gillard about the MRRT squeezed in between her activities with US President Barack Obama on Thursday.
