Opposition parties are targetting United Future leader Peter Dunne as they campaign to stop the Government from pushing ahead with partial asset sales.
Labour, Green and New Zealand First all say Mr Dunne should vote against partial privatisation, despite signing an agreement to support the Government.
They all say he did not campaign in favour of partial privatisation and should put a stop to the plan.
But Mr Dunne says United Future's deal with National ensures the Government will continue to have majority control of the assets.
Labour leader David Shearer says Mr Dunne's single vote could make the difference between flogging off assets and keeping them.
He says Labour will fight tooth and nail to prevent the sales.