The candidacy became vacant following the sudden death of Monte Ohia, from Canterbury, earlier this month.
Mr Ellison, who was one of three people who stood for selection in February when the late Mr Ohia was successful, believes the party should have endorsed the runner-up to that contest as the candidate rather than undertaking a new process. (The other candidate was lawyer Rahui Katene.)
While the runner-up at the February selection was not announced, Mr Ellison said party faithful at each of the eight hui at which candidates spoke stated clearly that each one of the candidates would have been supported.
He was concerned there would not be time for the new process to be as thorough as the February one and told party president Prof Whatarangi Winiata yesterday he did not want to enter the contest because of the process.
The party has begun a new selection process since Mr Ohia's death.
Candidates must be nominated by at least 25 financial members and have their completed candidate pack to the party by Friday.
Financial members of the party of Maori descent or on the Maori roll who live within the boundaries of the electorate, which takes in the whole of the South Island and Wellington, are eligible to participate.
Candidates will be publicly announced on July 7 and voting will be open to those who are financial members in the electorate as of July 5.
It is understood there will be hui before the voting is completed by July 13, but due to the short time available not all candidates may be able to speak at these meetings.
Mr Ellison has written to the party's national council raising his concerns about the process and communication issues around it.
Mr Ellison said he had a helpful conversation with Prof Winiata yesterday in which some of the background to the process decision was outlined, but it did not appear the council would change its stance.
Prof Winiata asked him to reconsider his decision not to stand.
Mr Ellison said as well as his concerns over the process, he was at a disadvantage because he had been out of the country and would be pushed to get everything ready by Friday.
Prof Winiata could not be reached for comment last night.
The candidate selection process in the Maori Party rules appears to allow for some variation, although the selection process overview does refer to hui to select candidates.
Clear notice of the nomination criteria and selection process to be followed is to be circulated and made available to eligible financial members at least two weeks before the nominations opening date, the overview says.
