Labour MP Shane Jones says deep divisions are opening up within the Maori Party as its members grasp the implications of the highly complex emissions trading legislation.
A Government bill amending the scheme has passed its final reading with the support of the Maori Party and United Future.
It waters down the existing ETS scheme passed into law by the former Labour-led Government last year.
Mr Jones says a number of Maori Party members have been contacting Labour to express their concern about the scheme.
"They've woken up to the prospect that less than 1% of the population gets this highly privileged concession in the South Island worth possibly up to $2 billion," he told Checkpoint, "and they're horrified by that prospect."
Maori Party MP Rahui Katene has defended the party's line, saying they'd stuck to it "despite the bitter opposition of others who prefer to rely on worn-out rhetoric".