The Green Party says Prime Minister John Key has created a situation where he is being held to ransom by SkyCity.
The Government will go back into negotiations with SkyCity to build an international convention centre in Auckland, following the release on Tuesday of a report from the Auditor-General's office.
In the report, Deputy Auditor-General Phillippa Smith found deficiencies in the process and that SkyCity was given preferential treatment but cleared the Government of any inappropriate conduct.
Green Party co-leader Metiria Turei said Mr Key's enthusiasm for the deal has put him in a disadvantaged position.
She said the Prime Minister has repeatedly said he wants the deal to go ahead so he has given SkyCity the advantage of being able to ask for anything.
Ms Turei told Radio New Zealand's Morning Report programme she has serious concerns about the Prime Minister's cosy relationship with SkyCity and wants the process reopened to all bidders.
Economic Development Minister Steven Joyce said in these situations bidders always want "a whole lot of stuff" but often don't end up with everything they want.
He said nothing has been set in stone, and once there is a conclusion the deal will be laid out for the public to have a look at.