Labour Party leader Phil Goff says the party is open to compromise in negotiations over the Emissions Trading Scheme.
Talks are set to resume next week between National and Labour on changes to the scheme.
The two parties have not met for at least three weeks. Mr Goff has written to the Prime Minister outlining his concerns.
He will now meet Climate Change Minister next week.
United Future leader Peter Dunne, who chaired a committee reviewing the emissions trading scheme, says he does not believe it will be impossible for the two parties to do a deal.
He says they agree on 32 of the 34 recommendations.