Greenpeace wants the Green Party to support the Government's Emissions Trading scheme and its plea could influence the decision MPs will make on Tuesday.
The Greens are putting pressure on the Government over key elements of the ETS which they want changed in return for backing it with their six votes in Parliament.
The Government hasn't got a majority without the Greens and New Zealand First, and time is running out for the bill to be passed before the election.
Greens' co-leader Jeanette Fitzsimons said yesterday her caucus would decide on Tuesday whether to support the bill.
She said the negotiations had failed to make progress on key areas such as agriculture and transport but ministers had agreed to substantial assistance for people to insulate their homes.
"It's a dilemma, it's a hard decision and certainly the outcome is not decided," Ms Fitzsimons said.
But Greenpeace isn't in doubt about what the party should do.
"It is imperative that New Zealand's emissions trading scheme is passed into law this parliamentary term," said senior climate campaigner Simon Boxer.
"This is very much a case of something being better than nothing. The climate is in crisis and New Zealand has virtually no policy in place to start addressing it."
The National Party is opposing the legislation that sets up the ETS, and Greenpeace condemned it for that.
"The National Party's calls for the scheme to be delayed...are irresponsible and must be ignored," Mr Boxer said.
"They are based on nothing more than the bleating of a core group of big polluting businesses."
Business New Zealand reacted to the Greens' dilemma by saying the legislation needed to be reworked.
"Our message to the Green Party is that we need an emissions trading scheme - but not this one," said Business NZ chief executive Phil O'Reilly.
Under the bill, all sectors of the economy will eventually come under a regime that sets limits on the amount of greenhouse gas they can emit.
Those that exceed their limit will have to buy units from those which are under their cap.
The transport and agricultural sectors will come under the scheme in 2011 and 2013.
The Greens want those dates brought forward but the Government apparently won't budge.
Negotiations between ministers, the Greens and NZ First are expected to continue during the next few days.
NZPA