MPs from the ACT Party are split in their support for a Government bill aimed at speeding up the court system.
National is negotiating with a number of parties to gain more support for the Criminal Procedure, Reform and Modernisation, Bill.
The bill is due to come before Parliament for its second reading, but that will not happen this week.
ACT's deputy leader John Boscawen says three of the party's five MPs support the bill, but he and Rodney Hide do not.
Mr Boscawen says they are concerned about possible intrusions on a defendant's right to silence, by requiring defence lawyers to set out their cases in advance.
