New Zealand First MP Andrew Williams is taking legal action against his party for dropping him as an electorate and list candidate for the general election.
Mr Williams who was ranked number three on the list in 2011, was removed from the list when it was published on Tuesday.
The MP says he has instructed his lawyers to file papers in the Auckland High Court seeking declarations that the New Zealand First Party breached its constitution when it determined its party list.
He believes he has been mistreated by the party and will ask for an urgent hearing following the election on 20 September.
Party leader Winston Peters said today that Mr Williams doesn't understand the New Zealand First constitution, which states that no candidate can breach of confidentiality in the list selection process.
On Wednesday, Mr Peters said Mr Williams was publicly critical of the list ranking process. He said the MP had breached confidentiality by talking to reporters about the list, when it was in its draft form.