The Liberal Party is in turmoil with the resignations of five frontbenchers from their portfolios this afternoon in protest against the emissions trading scheme.

Tony Abbott, Sophie Mirabella, Tony Smith and Senators Nick Minchin and Eric Abetz have all quit their portfolios because they cannot vote for the legislation.

Senate whip Stephen Parry has also relinquished his position.

The mass resignations will put huge pressure on Malcolm Turnbull's leadership after only just surviving a push for a spill yesterday.

The party whip had earlier instructed MPs and Senators not to leave the building but it is understood they have now been released.

The resignations began this afternoon after Mr Abbott and Senator Minchin confronted Mr Turnbull, urging him to put off a vote on the scheme until February.

Mr Turnbull refused so Mr Abbott handed in his resignation.

"This is a very difficult decision for me. I've always regarded myself as a very loyal party man," he said.

Mr Abbott has confirmed he will not challenge Mr Turnbull for the leadership.

But when asked if he would stand if the position became vacant he replied: "I can't say what might happen in the future but as far as I'm concerned this is a matter about policy."

Mr Abbott says he urged Mr Turnbull to reconsider his position after being inundated with calls and emails from voters.

"The phone lines have been in meltdown with people saying that the Liberal Party would not be doing its job as an Opposition simply to pass this thing without the scrutiny that people calling my office think it demands," he said.

After Mr Abbott announced his resignation, news that the other four had also quit quickly followed.

The party's emissions trading spokesman, Ian Macfarlane, is now in Mr Turnbull's office.

As the revolt unfolds in Parliament House sources say the Government has offered to gag debate on the ETS legislation, which is now underway, in order to bring on a vote.

It is understood that the offer is being considered but it is thought such a move would be unlikely to succeed.

Special meeting

The Senate is due to sit until Monday to vote on the scheme and Senators Minchin, Abetz and Parry say they will stay in their positions until then.

A special meeting of Liberal senators is now under way.

The Opposition's spokeswoman for early childhood and women, Ms Mirabella, says she also cannot support the scheme.

She says she decided to resign after the party room meeting on the ETS legislation "left a bitter taste in my mouth".

"It's not a decision that you take lightly," she told Sky News.

But Ms Mirabella denies the mass resignations essentially amount to a desertion of Mr Turnbull.

"It's not a matter of desertion. It's a matter of not being able to vote for bills that are so bad under any measurement," she said.

And she conceded she has never witnessed such extraordinary scenes during her time in Parliament.

"Quite frankly I hope not to experience another week like this," she said.

Yesterday Senators Mitch Fifield, Mathias Cormann and Brett Mason also offered to resign from their frontbench positions.