He took legal advice yesterday and said he would lodge his legal action this week, but declined to specify the exact nature.
Mr Morgan has been chairman since 2006, although his leadership term was interrupted in 2004 when he was removed from office because of a land protest conviction.
Whatever the outcome of his legal action, he said, this term would be his last on the parliament.
The fate of Huhana Marshall, who in two rounds of voting tied with Mr Morgan and was then narrowly beaten by him, is also uncertain. The tribe's rules also allow for a board member to be co-opted, further complicating matters.
In total, six board members lost their seats: Patience Te Ao, Charles Joe, Robert Tukiri, Maxine Moana-Tuwhangai, Taitimu Maipi and Mr Morgan.
The new board is yet to meet to select a chairman. Former tribal executive Hemi Rau, who was fired in 2009 for leaking information to the media, is a new board member, and former Te Kauhanganui chairman Tom Roa is also a new member.
Mr Roa said there was a call from within the tribe for a ceasefire on court action.
"I'm one of the people who have been critical of a number of steps of the outgoing Arataura so it's only right for me to put my name forward and to stand up and be counted."
Mrs Martin, who has been an adversary of Mr Morgan, said she felt "vindicated" by her return as parliamentary chair.
However, questions have been raised about the legitimacy of her mandate to represent Hiiona Marae.
Emails obtained by the Herald show a special general meeting was held in November revoking the mandates of Mrs Martin and two other marae representatives.
She said she was unconcerned about that challenge and it was an internal matter for her marae.
Mrs Martin said she believed Mr Morgan was behind the challenge.
VOTED IN
Members of Waikato-Tainui's executive board, Te Arataura:
* Hemi Rau.
* Kingi Porima.
* Marae Tukere.
* Paki Rawiri.
* Rahui Papa.
* Rukumoana Schaafhausen.
* Sonny Wilson.
* Tipa Mahuta.
* Tom Roa.
* Greg Miller (King Tuheitia's representative).
* One more.
Parliament's re-elected chairwoman
* Tania Martin.