The Government should have enough votes to make changes to the law governing its electronic spy agency after New Zealand First signalled it is likely to support the bill.
Under the changes, the country's electronic spy agency will be given the power to monitor New Zealanders on behalf of the police, the Security Intelligence Agency and Defence.
The New Zealand First leader, Winston Peters, said his party would vote for the changes as long as appropriate safeguards are put in place.
Both the Labour and Green Parties have said they won't vote for changes without first having an independent inquiry into the country's spy agencies.
But Mr Peters, who has criticised the Government's handling of the matter, didn't oppose the proposed change.
He said it was needed, and New Zealand First would support it as long as proper safeguards are put in place to prevent the Government Communications Security Bureau abusing its power.
The Prime Minister, John Key, said he believes safeguards can be written into the bill which will reassure New Zealand First.
Mr Key said he would brief opposition parties about the proposed law when the Intelligence and Security Committee meets on Tuesday night.
He said the Government Communications Security Bureau had helped to stop serious security threats to New Zealand.
But the Labour Party leader, David Shearer, is accusing the Prime Minister of sexing up intelligence information to justify rushing through the legislation without a full and independent inquiry.
Mr Shearer says no one knows what the real threat is, because Mr Key will not release details.
The term sexing up was used to describe a 2002 British Government dossier on Iraq's weapons of mass destruction, which has since been discredited.