New Zealand First leader Winston Peters says Parliament's new Speaker may have to be replaced if his performance does not improve.
David Carter replaced Lockwood Smith, who was appointed High Commissioner to the United Kingdom earlier this year. Both have been National Party MPs.
There were rowdy scenes in Parliament last week when Mr Carter ordered Labour's chief whip Chris Hipkins and senior MP Trevor Mallard from the debating chamber after a series of critical points of order.
Mr Peters told Television New Zealand's Q+A programme on Sunday that Opposition MPs are justifiably upset at Mr Carter's rulings, which he describes as unfair.
He says Mr Carter has not got past his political colours and is hindering MPs from doing their job of questioning the Government.
"He hasn't dropped the National Party background - and he's got to do that to be successful.
"If you talk about the romance and majesty of the job, it's to be Parliament's person - above all else, fearing no party or baggage or obligation. He's got a long way to go to get there."
Mr Carter has been in the job for just two months and Mr Peters says he is still hopeful his performance will improve.
On Saturday, Mr Hipkins said Labour is frustrated with the Speaker's rulings.