His comment follows a weekend hint by Opposition Leader Malcolm Turnbull that he might consider a deal then if the Government was willing to accept amendments.

The Opposition's current policy is that the vote on the Government's scheme should wait until after the Copenhagen climate conference is held in December.

Dr Washer said the Coalition needed to be part of the low-emissions economy and the country would be best off with a bipartisan approach.

But the legislation before Parliament was not satisfactory and should be amended, he said, although he had differences with the Coalition about the form the changes should take. The Coalition thought there should be better compensation for "dirty" industries, while he believed stronger price signals needed to be sent to the polluters.

Dr Washer said the main reason to get the legislation through soon was a political one: that the Coalition would not want to go to a double dissolution election on the emissions trading issue. This could happen if the legislation is rejected twice.

It is clear Mr Turnbull wants to avoid a double dissolution. He has pointed out that if the Government won, it would get its scheme through without change.

Dr Washer said that if a deal could not be cut in time for the vote that is scheduled when Parliament resumes in mid-August, he hoped the Government would allow a little more time before pressing for a vote.

If it wasn't possible to pass the scheme before Copenhagen, he said he hoped agreement could be reached on a bipartisan set of principles.

However, the Opposition's stance on the possibility of an early deal has been confused by varying statements from Mr Turnbull and his spokesman on emissions trading, Andrew Robb.

Asked on Sunday whether he would have a position by August, Mr Turnbull 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."

But Mr Robb insisted that Mr Turnbull "did not put a time frame on it". He said he had spoken with Mr Turnbull since his remarks "and I'm very clear on what was in his head".