The Greens could sink three key bills if the government does not ban new coal and gas exploration or expand its social policy fund, Greens leader Adam Bandt has warned – setting up a defining moment for the minor party and the Parliament.

At stake is the government’s plan to enforce its climate policy, and two other key planks of its election platform, multibillion-dollar funds to invest in Australian manufacturing and build social housing.

For the Greens, the bargain could determine how effectively they broker the balance of power but it is also reminiscent of a controversial moment in their history.

“You can’t put the fire out while pouring petrol on it,” Mr Bandt said.

Same old question

It’s a line Mr Bandt has deployed consistently, including when trying to attach a similar caveat while the Greens discussed whether to support the government’s target to reduce emissions by 43 per cent by the end of the decade.

Now the disagreement is about how to bring about emission reductions, and a policy to make Australia’s biggest industrial polluters shave 5 per cent a year off their total emissions or face financial penalties.

This was a “reheated Tony Abbott” policy with too many get-out clauses, Mr Bandt said on Wednesday.

(That comes alongside criticism that the government’s $15 billion National Reconstruction Fund for manufacturing could subsidise polluting industries. They also criticised the plan to build 30,000 homes as too small).

The party could set those concerns aside, he said: “If Labor agrees to stop opening new coal and gas projects.”

Only an offer

Those remarks have been interpreted in different ways, but Mr Bandt has denied giving an ultimatum to Labor.

He said he “had made an offer” to Labor, one that seems set to be followed by public negotiation.

Environment Minister Tanya Plibersek returned serve in question time when she accused Mr Bandt of jeopardising reform and potentially doing so by lining up with Peter Dutton and Barnaby Joyce to vote against the bill with the Coalition.

“(Greens voters) would be shocked to see the Greens voting with the Liberals and Nationals,” she said.

As government MPs observed, the Greens are familiar with the choice of reform or not at all before, when the Rudd government’s emissions trading scheme was twice sunk in the Senate.

Energy Minister Chris Bowen said the Greens would have to decide if they were “for the 200 million tonnes of emissions reduction or against it”.

The Greens former leader, Bob Brown, who scotched the emissions trading scheme, was urging Mr Bandt to hold the line.

When to compromise is a question that still divides the Greens.

Its more radical MPs opposed passing Labor’s pollution target in August, but wondered whether Mr Bandt had made the right call to make similar demands then only to fall in line.

Senator Lidia Thorpe has said she will vote with her old colleagues on climate policy now she’s an Independent on the crossbench.

That would put the government’s agenda in the hands of independent Senator David Pocock – who is sceptical but yet to declare his stance – and if Mr Bandt is serious, facing an uncertain future.