The Road Transport Forum - the lobby organisation for the trucking industry - wants the Government to remove uncertainty about when the new road user charges regime will be introduced.
Legislation to provide for the new regime has been delayed, in part because of Parliament's focus on special measures to deal with the Canterbury earthquakes.
The Forum says the protracted delays in passing the legislation are creating a climate of investment uncertainty, which is having a significant impact on business confidence and productivity in the road transport industry.
Its Chairman, John Hickman, says the industry is seeking assurances that every effort will be made to address that uncertainty.
But the Transport Minister, Steven Joyce, says it will be very challenging to get the legislation completed given the shortened House timetable due to the election in November.