A planned carbon trading scheme for Australia faces revision and possible delays from a Senate inquiry.
Draft laws on the proposed emissions trading scheme will be issued later on Tuesday.
The government wants them passed by the end of June, but Climate Change Minister Penny Wong has conceded the laws might not pass by the deadline of July.
The opposition and the Greens have struck a deal to ensure a two-month Senate committee inquiry will look at the scheme and alternative approaches.
Greens Senator Christine Milne said on Tuesday the inquiry would hear evidence from all possible sides.
Conservative MPs want the start of the scheme delayed until 2011 or 2012.