The Coalition this week announced it would push for a delay on the legislation of the Government's proposed carbon pollution reduction scheme until after a global meeting on climate change in Copenhagen last this year.

A delay in the vote until after Copenhagen will, in the eyes of the courts, effectively see it defeated.

The issue is looking more and more like a double dissolution trigger because Prime Minister Kevin Rudd has refused to delay the Bill and will push ahead to have it introduced next month regardless.

The Coalition offered what leader Malcolm Turnbull called "united" bipartisan support for the Government's emission reduction targets, but wants a vote on the legislation and the detail on how to reach those targets left until the global meeting.

The Coalition says it is also important to wait and see how the United States proposes to deal with emissions, and argues there is no imperative for the Government to have this Bill introduced in June.

The Nationals have vowed to vote against the legislation now and later if kept in its current form because the financial impacts on regional areas, farmers and miners will be disastrous, they say.

The joint-party room decision to push for a delay effectively vindicates The Nationals long-standing opposition to the emissions trading legislation, but could ultimately cost them in the Senate if the climate change issue triggers a double dissolution and early election, as widely expected.

If an early election is called, either late this year or early next year, all Senate spots will be decided instead of the usual half-Senate election.

In this event, it is most likely only one of the NSW Nationals Senators Fiona Nash or John Williams would make it through on a NSW Coalition ticket.

Nationals Leader in the Senate, Barnaby Joyce, said a delay in the vote until after Copenhagen, if the Parliament goes through all the appropriate processes, would be a vote against it.

"You cannot be more definitive than to vote against the scheme to say you don't believe in it," Senator Joyce said.

"It is a ridiculous scheme, it is a scheme of political tokenism and opportunism that does nothing…it is just a gesture, and for gestures I will not vote.

"Accepting the targets is one thing, but we have to look at how we get to those targets – we're not signing ourselves up for anything."

He told Canberra journalists on Tuesday it would be "highly unlikely" that The Nationals would ever vote for a cap and trade system.

Senator Joyce would not say how much consideration was given to the prospect of a double dissolution when reaching the position of delaying the vote, but confirmed The Nationals had everything to lose if an early poll was called.

He said an early election would be "extremely bad" for The Nationals in the Senate, and conceded Senator Nash or Williams, or both, could lose their jobs.

"You've got to do what's right," Senator Joyce said.

"This is a program that will cut a swathe through the economy of regional Australia and through Australia as a whole.

"In time people will obviously treasure their jobs rather than a gesture that will do nothing for the climate.

"We have more political skin in this game than most.

"This is the thing that could bring about the loss of a job of some of my colleagues…

"But do you do things in here that are right or do you do things in here that are politically expedient?"

NSW Nationals Senator John Williams said he accepted that voting down an ETS could cost him his job, but he would rather that than "betraying" rural people.

"I would rather walk out of this place with a clear conscience knowing I've voted against a policy that will the rural economy, rather than betraying my constituents to save my job," Senator Williams said.

"Rural people come before my job."