The emissions trading system (ETS) is a key element of the government's plan to curb greenhouse gas emissions, blamed for global warming, and was a major promise in the election that swept Labor Prime Minister Kevin Rudd into office in late 2007.
But the government needs an extra seven votes to pass the ETS laws through the Senate, where the opposition, minor parties and two independents all plan to vote against the current plan.
"I don't know how any parliamentarian could vote for this legislation," independent Senator Steve Fielding told local radio, adding Australia should first wait to see what other major countries do to curb emissions.
The government wants the ETS to start in July 2011, and has set a target to cut emissions by up to 25 percent if developed nations agree on tough action at global climate talks in Copenhagen in December.
Australia's scheme aims to cover 75 percent of the nation's carbon emissions from 1,000 of the biggest polluters, who will need a permit for every tonne of carbon they emit.
The current plan guarantees compensation to big polluters, with major emitters such as iron and steel manufacturers and aluminum smelters to receive 95 percent of carbon permits for free in the first years of the scheme.
The government wants the laws passed by the end of the Senate sittings, saying business needs certainty to plan for the ETS to start in mid 2011.
But the conservative opposition Liberal and National parties want to delay a vote on the ETS until after December's Copenhagen climate talks, while the five Greens Senators want the government to set tougher emissions targets.
Earlier, the opposition's manager of business in the Senate Stephen Parry unsuccessfully moved to delay debate on the ETS until later.
"We are down to the last possible week, we're down to the last couple of days. Let's get the urgent stuff done first, then come back to CPRS (Carbon Pollution Reduction Scheme) and debate it in a calm and rational manner," Senator Parry said.
National Party Senate leader Barnaby Joyce, a strong opponent of the carbon trade scheme, said he would use any tactic to prevent a vote on the laws.
"I want this debate to go for as long as possible. Call that a filibuster, call it what you want, call it you're aunt Mary, I will debate this thing until there is not a breath left in me," he said.