Labor governments in Victoria, Queensland and the ACT are demanding a future federal government has more scope to make deeper future cuts to greenhouse gas emissions.
With the NEG hanging in the balance, the united stance is aimed at maximising pressure on Energy Minister Josh Frydenberg to go much further than his latest proposal for a review of the target in 2024.
The state negotiations are influenced by calls from environmental and business groups for greater flexibility in how the target is adjusted, including a contested proposal to increase it without needing legislation.
Mr Frydenberg revealed the 2024 review as a concession to states last week, but critics have rejected it as meaningless as the terms of reference are not clear and the states have no input to the target.