Internet entrepreneur Kim Dotcom's extradition could be decided by Labour or Greens, one of which says it will not allow him to be sent to the United States.
The FBI is seeking Dotcom's extradition to the US on charges of criminal copyright violation.
But the Justice Minister has the final say on an extradition order, and a new government could be more likely to block Dotcom's extradition.
The extradition hearing was set for July 31, and may not be resolved before the general election.
Greens leader Russel Norman told 3 News that a Greens government would probably fight to keep Dotcom in New Zealand.
He said that he did not support the extradition process.
"I just don't think it's fair ... look at the way they have been acting illegally against him ... They illegally raided his mansion, they illegally obtained evidence, they illegally gave the evidence to the US Government against the directions of a judge.
That is not a lawful or fair process.''
Labour leader David Cunliffe this morning rejected any suggestion that Labour would block an extradition order.
He said the court process so far appeared to show the Government's actions were flawed, but he respected the separation between the judicial process and political matters.
Prime Minister John Key said opposition parties were "foolish'' for discussing an intervention in Kim Dotcom's extradition.
"We have an extradition treaty with the United States. In my view this is not a political issue. This is an issue where the United States is invoking the extradition treaty.
"Mr Dotcom is before the courts, and I actually think it's very foolish of politicians to personalise a particular issue.''
Asked whether the Government was likely to comply with the court's decision on Dotcom's extradition, he said that the Justice Minister Judith Collins had the final say and she would he have to be satisfied with the process.
Mrs Collins said it was irresponsible to comment on the outcome of an extradition order before it had been referred to the minister by the court.