Genesis Energy, the owner of the giant Huntly power station, may be first on the block if National wins the election - but Prime Minister John Key yesterday pledged new legislation to prevent any single shareholder from owning more than 10 per cent.
Mr Key's Government is under increased pressure to reveal details of its plan to sell up to 49 per cent of the three state-owned power companies and coal company Solid Energy and a further 23 per cent of Air New Zealand.
Labour and the Greens say the Government is withholding information regarding issues of foreign ownership of the shares in the companies National will sell in the next three to five years to raise up to $7 billion.
Asked yesterday which of the five companies marked for the "mixed ownership model" would be first on the block, Mr Key said, "It may be something like Genesis".
Solid Energy was the least likely to be up first and Meridian, which generates about a third of New Zealand's electricity, had a new chief executive - "so they'll work their way through that", Mr Key said.
The Government has sought to address concerns that control of the companies will eventually slip out of its hands, saying ownership of shares by any single individual will be capped at 10 per cent.
Mr Key yesterday said that would be achieved through legislation.
"We can just make that as law. There's an historical precedent there, Telecom had a cap. It's just a matter of passing legislation."
But Labour's finance spokesman, David Cunliffe, said the suggestion of a legislated shareholder cap was an attempt to appease voters worried about the assets being sold to foreign interests.
"He refuses to say what he will do to stop shares going offshore - because he knows there's nothing he can do.
"John Key's assertion that shares will remain in the hands of 'ordinary New Zealanders' is a fairytale. National is refusing to implement any restrictions on the overseas sale of shares. Indeed, Treasury told National that 'significant participation by foreigners would be essential'."
The Greens, who have accused Ombudsman Beverley Wakem of helping National suppress key advice about foreign ownership of SOE shares, yesterday vowed to do "everything it can to stop asset sales".
"We will use whatever power the New Zealand public gives us to keep our assets Kiwi," co-leader Russel Norman said.
While the policy has barely dented support for Mr Key, Greens co-leader Metiria Turei said it was clear that many National voters opposed asset sales. That gave her hope National would back down as it did on mining Schedule Four conservation areas.
"Just as with the mining campaign. Many thousands of those who marched in the street against mining in our national parks voted for National but they did not want that policy [to] proceed. We were able to be the political influence that helped prevent that alongside the community ... We think we can do that again in the future."
However, while retaining state-owned assets would be a "top priority" in the event it held post-election talks with National, the Greens stopped short of making it a bottom line.
"Kids, rivers, jobs, those are our priorities and we're not going to sacrifice a whole bunch of welfare things, we're not going to trade off one thing against the other.
"These are all critical issues for the Greens and keeping public assets is one of those issues."
Whether the asset sales plan goes ahead could ultimately rest with the Maori Party, should it form a coalition with National.
This week co-leader Pita Sharples said his party did not support asset sales.
However, he indicated they may not necessarily block National from going ahead with the sales.
"While our party position is that we oppose the sales of assets, we are also placed with the responsibility of advancing the best position for our constituency.
"Unlike other parties, that means we need to listen and respond to the proposals our constituents put forward to parliament.
"If iwi decide accordingly, then our position is that the Maori Party will support iwi who wish to invest into state-owned assets as a means of retaining New Zealand ownership."