The government is under fire from NZ First and its ally the ACT Party as parliament begins a marathon debate on the Resource Management Bill.
The huge bill is in its committee stage, when each clause can be debated and amendments proposed by MPs who aren't happy with its provisions.
It makes sweeping changes to the Resource Management Act, mainly to make it easier to free up land for housing.
Last month the government secured the support of the Maori Party to pass the legislation through its remaining stages by offering enhanced iwi participation in the decision-making process.
ACT leader David Seymour says there's been another, last minute compromise.
"Just this afternoon, hours before the changes are set to be debated, and with no consultation, National and the Maori Party have confirmed a compromise to allow ministerial override of local plans - except in the case of local GE-free policies," he said.
"This is compromise at its worst - a nonsensical mash of different positions that leaves everyone unhappy or confused."
Mr Seymour says National supporters are contacting him "dumbstruck at the concessions their party has handed to iwi and the green lobby".
Earlier on Tuesday NZ First leader Winston Peters said reform should be based on the principle of "one law for all".
"This country is about to go down a racially divisive abyss and the only ones who can do something about it is the National Party caucus," he said on Tuesday.
"It's time for them to step up."
He has sent a letter to each caucus member asking them to suspend the Bill's passage.
But Maori Party co-leader Marama Fox says Mr Peters is "off the mark".
"We've been negotiating this for two years and this is fundamental to a greater say for Maori and the protection of the environment for all people," she said.
Prime Minister Bill English called Mr Peters' letter "game playing" and said changes to the RMA would make it cheaper, easier and faster for councils to make decisions.
He said nothing in the iwi consultation provision changed the council's decision process but meant faster processes where councils and iwi could agree on which consents were sent for consultation.
Mr Seymour has announced he will seek to introduce four amendments during the bill's committee stage.
He also wants to abolish the provision that would allow the environment minister to override council planning decisions.
That was one of the conditions Act and United Future urged the government to drop in exchange for their support passing the legislation through its final stages.
Instead the government reached an agreement with the Maori Party to streamline iwi participation in exchange for their two votes.
Environment Minister Nick Smith is in charge of the bill.