The Greens and United Future are at odds over moves to change in-work tax credit entitlements.
Parliament will debate tonight the Member's Bill of Green co-leader Metiria Turei that would extend the credit to beneficiaries.
United Future MP Peter Dunne says the bill destroys the incentive of Working for Families to get beneficiary families into work.
"I don't really see there's much to be gained from having a discussion at a select committee, when there's such a fundamental difference of view."
But Metiria Turei says she's offered major compromises to Mr Dunne to get his support and he's turned them all down.
"Peter Dunne committed himself at the last election to a campaign to reduce inequality. Now is the chance for him to have the discussion on how we can do that and he's refusing to."
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