Green Party co-leader Russel Norman says a proposed referendum on partial asset sales could create major political problems for the Government.
A petition being launched by Grey Power and the Council of Trade Unions will need the signatures of more than 300,000 eligible voters to force a citizens-initiated referendum.
Dr Norman said he is confident people will support a referendum, and it would be hard for the Government to ignore the will of the public.
"People don't want to see the infrastructure assets that have been built up for generations sold off because of a problem created by the Government - the deficit that they themselves created."
The Government plans to sell up to 49% of state-owned companies Genesis, Meridian, Mighty River Power and Solid Energy and reduce the Crown's shareholding in Air New Zealand.
Dr Norman says a successful referendum could create uncertainty in the asset sale process because investors could be reluctant to buy into companies subject to ongoing political debate.
CTU president Helen Kelly told Radio New Zealand's Morning Report programme that opinion polls show the majority of New Zealanders are against asset sales.
Speaking in Parliament on Monday, Prime Minister, John Key, insisted that last year's election gave the Government the mandate to sell the assets.