Barnaby Joyce, leader of the Nationals, said he and his colleagues remain open to the target but want to consider a plan before making a firm commitment.
In a bid to tackle the climate crisis the European Union, Japan and the Republic of Korea, together with more than 110 other countries, have pledged carbon neutrality by 2050, while China says it will do so before 2060, according to the United Nations.
Australia has not yet set a goal for reducing carbon emissions.
In an interview broadcast on ABC's Insiders programme over the weekend, Mr Joyce bizarrely compared reducing emissions to ordering a meal in a restaurant.
“Generally how restaurants work is you go in and have a menu and they have what’s on the menu for lunch and what the price is,” he said.
“That is how a competent decision is made and that’s what we’re looking for. What’s on the menu and what the price is."
My Joyce is currently serving in a coalition government with prime minister Scott Morrison's Liberal Party.
“Until you lay down a plan, and show us the costs, you haven’t arrived at a point of consideration. Now, show us the plan, show us the cost and we’re happy to consider it and the National party room will do that,” he said of the net-zero target.
Backbenchers urged the prime minister to commit before the UN summit and called on him to restore funding and advisory powers to a government climate body.
“Never has a Liberal government been so out of step with the Australian business and investment community on a key issue as the current government led by Scott Morrison,” Zali Steggall, an independent MP, said.