Opposition MPs have put up dozens of amendments in an effort to slow the process of partial asset sales legislation through Parliament but have so far been unsuccessful in attempts to make significant changes.
The Mixed Ownership Model Bill allowing for the part sale of four state-owned energy companies progressed through its committee stages in Parliament on Tuesday.
The Government plans to sell up to 49% of its shareholding in Genesis Power, Meridian Energy, Mighty River Power and Solid Energy.
Opposition amendments sought to make the four companies subject to the Official Information Act and to block those companies from being removed from the State-Owned Enterprises Act in the first place.
The Maori Party voted with the Government against most of those amendments, but opposed the substantive bill.
Labour, the Greens and New Zealand First argue the legislation will drive up power prices and result in the shares being owned by foreign investors.
Prime Minister John Key says the partial sales are needed to keep debt under control, and the Government is considering measures to encourage New Zealanders to buy, and hold onto, shares.
New Zealand First leader Winston Peters is pledging to buy back any shareholding sold under this legislation, if the party holds ministerial posts in the future.
Meanwhile, Labour's state-owned enterprise spokesperson Clayton Cosgrove says an investor loyalty scheme will not stop New Zealanders selling energy company shares to overseas buyers.
"When they get their free share ... they'll do what they did with Contact Energy and other SOEs that were sold off by the National Government - they'll sell it for a higher price, and that's likely to go overseas."
State-Owned Enterprises Minister Tony Ryall says evidence he has suggests New Zealanders will buy out overseas shareholders.
Mr Ryall says New Zealand shareholders in Port of Tauranga, which is close to a mixed ownership model, are in fact buying out people from overseas.
"So I simply don't accept this idea that New Zealanders are going to flog their shares off," he told Morning Report.
On Tuesday, Prime Minister John Key said the Government was waiting on official advice before it committed to an investor loyalty scheme.
The Mixed Ownership Model Bill is expected to have its third and final reading next week.