Tony Abbott will challenge Malcolm Turnbull for the Liberal leadership on Monday.
Mr Abbott is one of several frontbenchers who resigned yesterday over dissatisfaction with Mr Turnbull's handling of the emissions trading scheme legislation.
He says if Mr Turnbull refuses to change his mind on the bill today, there will be a leadership spill on Monday.
"I will be talking to colleagues this morning. If there is no movement from the bunker then I'll be calling a spill for Monday morning," he told Macquarie Radio today.
AAP is reporting that Mr Abbott confirmed he would be a contender for the leadership.
Mr Turnbull this morning attacked Mr Abbott and the party's climate-change sceptics, including Nick Minchin and Eric Abetz, who also quit the shadow cabinet yesterday after unsuccessfully attempting to cajole Mr Turnbull into delaying the legislation.
He said he would not step down. The ETS bill is due to be voted on in the Senate later today.
"I will not step down. I'll stay leader until the partyroom removes me as leader," he said.
"I will not take a backward step, there's too much at stake. It's just not the credibility of the party."
He attacked the climate sceptics in the party, accusing them of trying to damage the Liberal party.
Mr Turnbull said the Liberal Party would be wiped out at the next federal election if it is fought on the issue of climate change action.
He said the public would not view the issue as being about the intricate designs of an ETS, but which party was more willing to take action on climate change.
"The Australian people want their government to get on with the job of taking action on climate change," he told ABC this morning.
"It's not just a question of our political credibility, but a question of our integrity," he said, arguing the Liberal partyroom had agreed to the deal struck with the Government and that should now be honoured.
Mr Turnbull was confident the amended legislation would be passed by his supporters in the Senate.
"I'm confident that the Senate or a substantial number of them will act in accordance with the decision of the shadow cabinet and endorsed by the party room."
But he noted that "there's a minority in the Liberal Party who will do anything to ensure the party does not take action on climate change", singling out Sen. Minchin and his belief in a left-wing conspiracy as an example.
Mr Abbott said that even if the ETS bill was passed today it could be stopped on Monday.
"My understanding is regardless of anything that might happen in the Senate today, it will still be possible on Monday to send this bill off to a committee so it can be properly scrutinised over the summer,'' he said.
The bill would not be law until it was passed through a third stage on Monday, Mr Abbott explained.
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