Challenger Kevin Andrews has threatened to delay a vote on the Government's emissions trading scheme if he unseats Malcolm Turnbull in a possible Liberal leadership spill this afternoon.

Mr Turnbull has put his leadership on the line by calling a party room meeting for 1pm AEDT to decide on whether or not there will be a leadership spill.

Mr Andrews has confirmed he will run if a spill is called after the initial show of hands in the party room. But Tony Abbott and Joe Hockey say they will not stand against Mr Turnbull.

Speaking at Parliament House this lunchtime, Mr Andrews said he was offering to stand because he did not believe that Mr Turnbull's decision to back the Government on emissions trading represented the views of the majority of Liberal Party members.

Mr Andrews said he would refuse to back the emissions scheme in the Senate this week if he was elected.

"The reason I'm doing this is because I believe that the decision, or the reported decision that was taken yesterday did not reflect the views of the majority of Liberal Party members throughout Australia about this issue.

"[The ETS scheme would] make the GST pale into insignificance in terms of its impost on the nation."

He said he would withdraw support for the emissions trading scheme if elected as leader, and would seek to send the legislation back to a Senate committee for more scrutiny.

Prime Minister Kevin Rudd has said he wants the legislation passed by the end of the week before parliament rises for the Christmas break.

Mr Andrews denied suggestions he was not a legitimate leadership candidate.

"I wouldn't be standing here if I didn't want the job," he said.

And he said he was "quite sceptical" on whether humans were causing climate change.

"The jury is still out."

The ABC has confirmed that three senators who have previously spoken out against supporting the ETS have offered their resignations from the frontbench - Mitch Fifield, Brett Mason and Mathias Cormann.

Mr Andrews has held the Victorian seat of Menzies since 1991.

He first rose to prominence in 1996 by sponsoring the private members bill to overturn Northern Territory legislation legalising euthanasia, and is a prominent member of the now-defunct conservative Christian Liberal faction, the Lyons Forum.

Mr Andrews has also been outspoken in his opposition to a number of birth control reforms as well as the use of human stem cells for research.

In the Howard Government he served as minister for ageing, before being appointed the minister for employment and workplace relations and finally immigration minister.

It was during his tenure as immigration minister that Mr Andrews came under fire for his handling of the Mohamed Haneef scandal.

He has also been criticised for his outspoken stance on Muslim immigration, recently being branded as racist for his claims Muslim immigrants were not assimilating into the community.

Mr Turnbull last night stamped his authority on the party by declaring it would support the Government's revamped emissions trading scheme and vote for it this week.

This morning he reiterated his position that there was a clear majority from the party room endorsing his position and dismissed calls for a spill, saying there was no credible support for one.

The initial motion for a spill has been brought on by backbenchers Wilson Tuckey and Dennis Jensen, who were calling for a party room meeting tomorrow morning.

But a party room meeting to have a vote on Mr Tuckey's motion today was later confirmed by Mr Turnbull's office.

Mr Turnbull's earlier refusal to agree to hold the meeting prompted accusations from Mr Tuckey he was running from a ballot.

"I know now that Malcolm Turnbull has dodged the spill he said we should call," Mr Tuckey told ABC 2.

"Yes, I'm destabilising the Opposition leadership - quite deliberately - but during proper process. Yes, it'll shut me up if the party endorses him, but if he doesn't front, it won't shut me up.

Mr Tuckey says Mr Turnbull's leadership must be tested with a vote and he believes the numbers in the party room yesterday were clearly against the scheme.

"I've never, ever, seen the day when the leader would question whether we're going to have a meeting as called," he said.

"He believes that he's been elected and nobody else's opinion matters

"In my opinion he will continue to drag us to a position where we'll be lucky to return to this place with 10 or 12 seats and he won't be one of them."

Mr Jensen has accused Mr Turnbull of "ripping our party apart" and says there is more support within the party for a spill than just him and Mr Tuckey.

"This is something that happened as a result of the behaviour of Malcolm last night," he said.

Mr Turnbull has refused to spell out how many spoke for and against the scheme but Dr Jensen says the numbers who spoke against were "well over 40".

Meanwhile, another backbencher Peter Slipper has likened Mr Turnbull to Zimbabwean dictator Robert Mugabe.

"Look, the result of the party meeting as declared by the leader last night was about as dodgy as a Zimbabwean election organised by Robert Mugabe," he said.

But senior shadow cabinet members have rallied around Mr Turnbull this morning, scoffing at suggestions there are any serious challengers who could topple Mr Turnbull.

"If a meeting arises Malcolm will secure the numbers comfortably," climate change spokesman Ian Macfarlane said.