TONY Abbott will address a rally of climate sceptics in Canberra today as the Opposition tries to defend Labor accusations that it is a party of climate change deniers.

Strongly supported by right-wing shock jocks, the rally is expected to hear from a range of voices questioning the scientific evidence for climate change.

Scores of buses, filled with opponents of the planned tax, are heading to Canberra for a rally outside Parliament House this morning.

Prime Minister Julia Gillard plans to introduce a tax on carbon emitters from July 2012 but Mr Abbott has said under the coalition the best tax cut Australians can get is no carbon tax.

The rally will be seen as a key step for Mr Abbott and members of the Coailtion, who have been forced to defend themselves against accusations that they are a party of climate change deniers.

An alliance of conservative bodies is planning rallies across the country today against the Gillard Government's carbon tax with one of the largest expected outside Parliament House in Canberra.

The Opposition Leader is expected to address the Canberra rally and yesterday renewed his attack on the Prime Minister's pre-election promise not to introduce the tax.

He told parliament the PM suffers from truth deficit disorder and is clocking up frequent liar miles.

But trade unions are attempting to hijack the protest by delivering a petition in support of the measure to Climate Change Minister Greg Combet.

A coalition of climate change advocates - including the ACTU, activist organisation GetUp, the Australian Youth Climate Coalition, Greenpeace and others - also plans to take on the protesters.

ACTU president Ged Kearney and other union figures have already arrived to personally deliver a petition to Mr Combet prior to the 10.30am rally

The rally comes as manager of Opposition Business Christopher Pyne yesterday asked Ms Gillard during Question Time to withdraw the term "climate change denier".

Mr Pyne argued the term was used by Labor as a weapon to paint the Opposition as climate change extremists, The Australian reported.

Just days ago, Mr Abbott declared climate change was real after being attacked for telling a community forum that the science wasn't settled.

Mr Abbott said "whether carbon dioxide is quite the environmental villain that some people make it out to be is not yet proven".

He infamously declared in 2009 the science was "crap" but has since stated he accepts humans are contributing to global warming.

Meanwhile, steel boss Graham Kraehe warned that business has lost trust in the Gillard Government and that any proposed compensation scheme for emissions trading was like "putting a bandaid on a bullet wound."

Mr Kraehe, who is Bluescope Steel Chairman, said the carbon tax was ill considered and wouldn't give businesses enough time for consultation.

He called for a sector-by-sector approach to carbon pricing or carbon tariffs.

However, the warning is unlikely to be acknowledged by the Government with Julia Gillard boosted by a strong recovery in the latest Newspoll which put her ahead of Mr Abbott as preferred Prime Minister.

The Prime Minister is aggressively pushing the case for a carbon tax both in the media and parliament, despite being hampered by a lack of detail on the controversial tax.

Read the latest Newspoll results (PDF) from The Australian.