Any changes to the Emissions Trading Scheme will be finalised in late 2019, meaning if they are delayed they could be decided in the heat of the 2020 general election.
Shaw said he was confident the issue could be resolved before election year.
"We could do this in a hurry in order to try to get in well ahead of the electoral cycle.
"The risk if you do that is you don't go through a thorough process, the kind of which we are engaging in here, you reduce the chances of getting bipartisan support for this."
He added: "We will try to get it done and dusted so it doesn't become a political football in 2020."
National Party climate change spokesman Todd Muller said the Government was again targeting regional New Zealand.
"The fact the first task the Government's committee has been assigned is how to bring agriculture into New Zealand's Emissions Trading Scheme shows a worrying lack of concern for our farmers and economy.
"Forcing agriculture into the ETS before we have the technology available to reduce emissions without culling stock will amount to nothing more than another unfair tax on farmers and regional New Zealand."
But Business NZ and Federated Farmers welcomed the new interim committee, saying it had a good mix of people with the right skills for the job.
Agricultural emissions make up around half of New Zealand's total greenhouse gas emissions, and Labour and the Greens have long called for farmers to pay their fair share.
However, Shaw conceded today that there was no guarantee farmers would be brought into the scheme once the interim committee reported back.
"The presumption has always been that at some point agriculture would become part of the Emissions Trading Scheme.
"But the caveat was always, what are the conditions that need to be met? And essentially they have not yet been met.
"So what we are doing is having a fresh look at those conditions and saying 'What are the circumstances that would need to be in place in order for that presumption to be fulfiled on?'
"And they might not be. But that's been the assumption for a long time."
He said if they were not made to pay for their greenhouse gases, the Government would have to find an alternative way to reduce its carbon footprint.
"Because we know that agricultural emissions not just in New Zealand but right around the world have ever come down."
Many countries around the world were looking to New Zealand for leadership on how to reduce agricultural emissions, he said.
Under the Labour-NZ First coalition agreement, farmers will only have to pay for 5 per cent of their emissions if they are included in the ETS.
That was non-negotiable and could not be amended by the interim committee, Shaw said today.
The Labour-designed ETS was initially meant to include farmers, but when National came to power it put off their inclusion in the scheme indefinitely.
The other members of the committee are Lisa Tumahai, chairwoman of Ngai Tahu for the last five years, former Parliamentary Commissioner for the Environment Jan Wright, agricultural greenhouse gas expert Harry Clark, former Meridian chief Keith Turner, and climate change and emissions trading expert Suzi Kerr.
