Although the Liberals want to delay making a decision until early next year, Mr Turnbull said on the weekend that "I've got no doubt we will have an emissions trading scheme in Australia".

"That's my view. The question is: what is its design?"

Conservatives and Nationals who oppose a trading scheme thought that when the Coalition voted last week to delay a scheme, it was implicit the Opposition would never support one.

In the party room yesterday, the maverick Wilson Tuckey rose to complain that Mr Turnbull had committed the party to a new position.

The Nationals senator Ron Boswell complained he had never consented during any party room meeting to support a trading scheme.

Mr Turnbull shot back by asking Senator Boswell rhetorically where he was before the last election when the Coalition, then in government, promised to introduce an emissions trading scheme as policy.

Senator Boswell protested that he "probably was" present at the time but "I just didn't understand it", sources said.

One Liberal said "Malcolm did a good job. He stitched him up".

But the right is wary. One MP told the Herald that a section of the party would never support a trading scheme. "There will be a showdown in three months' time," he said.

Mr Turnbull told the party room that the American model, which should be finalised next year, would be the global benchmark for schemes, and he envisaged supporting something similar.

The Government, however, will bring matters to a head later this month. Its bill for a trading scheme will pass the House of Representatives this week and there will be a Senate vote before the end of the month. The Coalition will oppose the legislation if its attempt to delay fails.

Labor will try again in October. If the Senate opposes it again, the Government would have a trigger for a double dissolution election.