Malcolm Turnbull has vowed to stay on as Opposition Leader and support the emissions trading scheme (ETS) despite mass frontbench resignations in revolt against his position.

Speaking at a media conference early last night, the embattled leader said the party must honour its agreement with the Government and allow the amended scheme to pass the Senate.

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And he said it would be a fatal and "catastrophic" move for the Liberals to be seen as climate change sceptics.

"This has now become a question not simply of the environmental responsibility of the Liberal Party but its integrity," he said.

"We agreed with the Government on this deal.

"We must retain our credibility of taking action on climate change."

But his decision to stand firm has not stopped some of his backbench colleagues from calling for his resignation.

Mr Turnbull was forced to front the media after spectacular events in Federal Parliament late yesterday which saw Tony Abbott announce he would quit his portfolio in protest against a vote for the ETS.

He was quickly followed by Senators Nick Minchin and Eric Abetz, Tony Smith and Sophie Mirabella and Opposition Senate whip Stephen Parry.

The resignations came after Mr Abbott and Senator Minchin confronted Mr Turnbull and urged him to put off a vote until February, but Mr Turnbull refused.

Mr Abbott and other Liberals say they have been inundated with calls from constituents who want the Liberals to reject the scheme.

Those who have resigned insist they have done so as a policy protest.

But with the loss of five frontbenchers, Mr Turnbull's grasp on the leadership is rapidly slipping.

A spill is looking likely for Monday when the House of Representatives is due to sit again.

The ABC understands that if a spill goes ahead and Mr Turnbull runs, Joe Hockey will not. But Mr Hockey has not ruled anything in or out if Mr Turnbull steps aside.

'I am the leader'

With supporters such as Christopher Pyne and Steve Ciobo in attendance at the media conference, Mr Turnbull said his decision to stick to his guns was about risk management.

"I am the leader of the Liberal Party and I was confirmed as such 24 hours ago in this room," he said.

He added: "We have to give the planet the benefit of the doubt. The fact is we have to take a prudent approach to this."

Mr Turnbull said despite the frontbench revolt, he would not be changing his position.

"Some of my colleagues have found it necessary to resign from their ministerial position - that is their right and I respect it," he said.

"But I believe we must maintain this course of action. It is the responsible thing to do and the honourable thing to do."

The Senate was debating the legislation last night and is due to sit until Monday.

Leader of the House Anthony Albanese said the Government would not move to gag debate tonight in order to bring on a vote.

But he said it would be voted on by the end of today.

"We have made a commitment with the Opposition that this will be voted on by 3:45pm tomorrow afternoon (Friday)," he said.

Mr Turnbull says the resigning senators will stay in their positions until the Senate rises and Senator Minchin has given him a "solemn undertaking" not to frustrate the passage of the legislation.

And he believes there are the numbers to get the legislation through.

Mr Turnbull says he will think about a reshuffle of his frontbench after Parliament rises next week.

'Party's heartbroken'

Despite Mr Turnbull's defiance, the mass resignations have caused massive damage to his leadership and several backbenchers who spoke out yesterday afternoon against him.

Former Liberal whip Michael Johnson says Mr Turnbull's has no choice but to resign and has called on deputy leader Julie Bishop to tap him on the shoulder.

"As the current Deputy Leader she needs to go and see Malcolm, if she hasn't done so already, and say, 'your senior shadow ministers are against you, your position is untenable'," he said.

Bronwyn Bishop said Mr Turnbull had to accept that the party did not want to vote for an ETS.

"They are so angry that their heart is broken. This is a new tax. It's against all the things we believe in," she said.

And Peter Slipper called on him to stand down.

"Malcolm Turnbull is paying a very heavy price for wrongly calling the result in the party room. I really think it's in the interests of the party room that he resigns as quickly and as decently as possible," he said.

In a statement released last night, Senator Minchin said he had no choice but to resign.

"Mr Turnbull declined this proposition so I advised that I would have no alternative but to resign from the Shadow Cabinet as I was not able to support the CPRS legislation," he said.

Speaking on Sky news, Senator Abetz said his conscience was clear.

"In my mind there is no doubt that a majority of people in the party room spoke against the proposal that was put before us," he said.

"Within my own conscience I'm satisfied I'm doing the right thing."

Senator Parry said he had to resign because the ETS was not right for Australia.

"I could not go back to my home state and look people in the eye and say I've voted for a scheme I know is going to seriously impact on the finances of small business and many Australian families," he said.

Mr Smith has also released a statement, confirming his resignation in which he says he rejects the argument that a vote against the scheme endorses inaction on climate change.

"Whilst not supporting my Leader's decision is difficult, not supporting the interests of my electorate is impossible," he said.

www.abc.net.au/news/stories/2009/11/26/2754779.htm