Nationals senator Bridget McKenzie has conceded her colleagues will have no opportunity to cross the floor in protest against climate change targets.
Nationals backbenchers Matt Canavan and Barnaby Joyce have threatened to vote against any legislation enshrining a target of net zero emissions by 2050.
But Senator McKenzie admits the goal will not need to be legislated.
The government can simply sign Australia up at a United Nations conference in Scotland later this year.
"My understanding is there will be actually no legislative requirement if the government decides to head off to Glasgow and sign this up," Senator McKenzie told ABC radio on Tuesday.
The target has been adopted by Australia's major allies including the United States, but locally it's creating fractures between the Liberal and National parties in government.
The target has been adopted by all Australian states and territories, and is also federal Labor's policy.
Opposition Leader Anthony Albanese says the government is falling behind the world on climate policy.
"It's quite preposterous that this government's having a debate about what should be excluded from a target that they haven't adopted," he told reporters on Queensland's Fraser Coast.
Senator Canavan thinks the climate debate is a distraction, as he continues arguing for a new coal-fired power station.
He says the exclusion of agriculture - which is being discussed within the Nationals as a bargaining chip with their Liberal colleagues - would not change his approach to the issue.
Excluding agriculture would put Australia in line with New Zealand's net zero by 2050 plans, which places a lower target on reducing methane levels.
Agriculture made up 13 per cent of Australia's greenhouse gas emissions last year and the percentage is expected to rise to 2030 as the effect of the drought eases.
The National Farmers Federation supports net zero by 2050 but wants to ensure the sector isn't left worse off.
Independent MP for Warringah Zali Steggall is calling on Prime Minister Scott Morrison to discuss her climate change bill, which locks in net zero by 2050 and creates a Climate Change Commission.
"The Nationals are trying to paint this transition as a binary choice - jobs or emissions," she said.
"This is a once in a generation opportunity for Australia to take the lead and prosper."
The European Union's ambassador to Australia has confirmed a free trade agreement between the two partners will not include climate tariffs.
Michael Pulch said everything the EU does is to support climate action.
"But a free trade agreement is a free trade agreement and our cooperation on climate change activities are separate from them," Dr Pulch told ABC radio.
"Although, in the free trade agreement we have a chapter on sustainable trade which is very important to us."
Australian Associated Press