But Greens climate spokeswoman Christine Milne believes a deal - which would also need the support of Independent senator Nick Xenophon and at least one rebel Liberal senator - remains a possibility.

Senator Wong said she was willing to talk to the Greens but the Government could not accept the minor party's target of a 25-40 per cent cut in emissions by 2020.

''We have said we are willing to have a discussion with the Greens and other cross-bench senators with a view to getting this legislation through. The reality is, though, the Greens have taken a position in relation to targets that the Government was not able to negotiate on,'' she said.

The Government would not increase its emissions reduction targets, which ranged from a minimum of 5 per cent to 25 per cent, depending on what other countries agreed to at Copenhagen.

The Copenhagen climate change conference produced an accord to keep global temperature rises to less than 2 per cent.

Senator Milne said it was time the Government rethought its targets. ''Australia now has to submit by January 31 to the UN FCCC [Framework Convention on Climate Change] its proposal for economy-wide emission reductions and its targets,'' she said.

''So really, after the Copenhagen experience all developed countries should review their situation and, as the secretary of the FCCC said, countries should go for the most ambitious target. It's now up to Prime Minister [Kevin Rudd] and Minister Wong to lift the level of their ambitions.''