Outspoken Nationals senator Matt Canavan would consider crossing the floor of parliament on climate or energy policy if it wasn't in the interests of his Queensland constituents.
Senator Canavan, who returned to the back bench as a result of the recent leadership spill in the National Party, is a strong supporter of coal for Australia's energy source.
Asked on Sky News whether he would be willing to cross the floor and vote against the government on climate or energy policy, Senator Canavan said: "Well, the short answer is yes, the longer answer is it depends on the detail."
"The key thing ... if it's against the interest of my constituents."
He said every backbench member of the coalition has the right to form their own position on legislation.
"While I'm on the back bench, I'm not intending to take a back seat," he said on Sunday.
He supports the government's Paris emissions reduction targets, saying they are realistic and responsible.
But he doesn't believe in taking any further unilateral action without other countries moving.
He doesn't support committing to net zero emissions by 2050, as the states and territories have done, as well as dozens of other countries.
"How as a country can we commit to net zero emissions in 30 years' time ... it seems so fantastical to me," Senator Canavan said.
"It's seems like the kind of thing that governments say because they are not doing much today, but they'd like to try and hoodwink people that they might do something in 30 years' time."
Nationals Leader Michael McCormack said 2050 is a long way off and he doesn't know what technologies are going to be invented in the next 30 years.
But he doesn't want to go down a path that would end up sending manufacturing jobs offshore.
The Intergovernmental Panel on Climate Change says emissions must be cut to zero by 2050 to avoid a global temperature rise of 1.5 degrees Celsius.
"The IPCC is not governing Australia. The Liberals and Nationals are," he told ABC television's Insiders program.
"We're not run by international organisations."
Australian Associated Press