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.