Only 25 per cent oppose it, while 65 per cent back the scheme, on which a vote was deferred last week. Of those opposed, the main reasons were that Australia should not go it alone, it would damage the economy, climate change is not caused by human activity and the emissions reduction targets should be larger.

Labor voters (79 per cent) and Green voters (74 per cent) are more in favour than Coalition supporters (46 per cent). Women are more likely to back the scheme than men, and those over 55 are less likely to support the scheme than younger voters.

The Opposition's policy has been that a Senate vote should wait until after the December Copenhagen conference. But the passage late Friday of the Waxman-Markey climate change bill through the US House of Representatives — it still has to pass the US Senate — is increasing the heat on Mr Turnbull to try to cut a deal early.

Mr Turnbull said that over the winter parliamentary recess Frontier Economics was being commissioned to do a detailed study of the sectoral and regional impacts and compare it with different approaches.

The Opposition has joined with independent senator Nick Xenophon to commission this study.

"Given that Mr Rudd is not prepared to do the sensible thing and postpone the completion of the scheme until next year, until after the Americans have finalised their position enough in Copenhagen, it will enable us to come back with amendments that we would propose to the legislation" he told the Ten Network.

Mr Turnbull suggested possible amendments the Opposition would present include more support for coal mining and carbon capture in soil and trees.

Asked whether he would have a position by August, he said the Opposition had a range of criticisms but "we will be able to present amendments and hopefully the Government will accept them. If the Government doesn't accept them, then, of course, we'll have to work out what happens next".