Two political parties oppose a deal that would allow a casino operator to expand its gambling operation in return for building a convention centre in Auckland.
Sky City has been chosen by the Government to build a $350 million centre, for which it would not require any Government funding.
In return, the company wants the Government to extend its casino licence and change the law to allow it to add gambling tables and machines.
Sky City was the only bidder not seeking Government funding, but wants a law change to allow it to add gambling machines and tables to its casino.
The Maori Party is against the trade-off and the Green Party calls it a public-policy-for-sale approach.
Prime Minister John Key says any law change would be open to public submissions.
Economic Development Minister David Carter told Morning Report the finer details are still being discussed, but the public will be consulted.
Mr Carter said he does not think a moderate increase in gambling machines at Sky City will increase problem gambling, because it will be in a regulated environment.
Auckland Council member Richard Northey, who is on the board of the Problem Gambling Foundation, says a new convention centre will lead to more problem gambling and domestic violence.
He says the Government has sold its law-making powers and pushed the problems onto poorer Aucklanders, to get a convention centre on the cheap.
He plans to raise the issue at the council.