Labour and National have their first major disagreement in the new Parliament over the number of MPs serving on select committees.
National said changes to MP representation means its ability to hold the new government to account is being compromised.
The number of MPs who will sit on select committees has been reduced, but Leader of the House Chris Hipkins said that was because of an agreement all political parties signed up to in the last Parliament.
Simon Bridges, the shadow Leader of the House, said having fewer seats would mean 11 National MPs would miss out on sitting on a select committee.
"That will mean for National effectively more MPs than the whole New Zealand First caucus won't be able to do what they went to Parliament for on behalf of their communities."
Select committees are cross-party groups of MPs that consider legislation, scrutinise the actions of ministers and government departments and have the power to hold inquiries, like the recent one into voluntary euthanasia.
Usually there are as many committee seats as there are MPs in the House, but there are no firm rules around this.
The seats are then allocated proportionally among the parties.
Mr Hipkins said as a result of the changes there would be 12 select committees and in a move of good faith the Government had offered National the chairperson role on five of those committees, along with five deputy chairperson positions.
He said given the make-up of Parliament the governing parties of Labour, Greens and New Zealand First would only have a majority on about four select committees.
"The days when governments can just do what they liked and railroad over the top of the opposition have to come to an end, but what the National Party seem to be asking for is a blank cheque to stop the government being able to govern."
Prime Minister Jacinda Ardern said the degree of "sharing" from the government side was "extraordinary" when compared to past Parliaments.
"To then be described as operating in an undemocratic way I find to be completely unfair."