"We appreciate and understand the restraints on available capital funding. However the regions have missed out to the metro cities for the last 30 years.
"The improvements are a small amount of money in comparison to other roading projects and it seems nonsensical to continue putting the project on hold.
"The first stage of the project was to simply designate the road, providing residents a clear understanding of what is expected, and allowing them to plan their lives.
"Last year NZTA's approved designation was very much a compromised position that the region reluctantly accepted. For this initial piece to now be deferred indefinitely is untenable.
"As a region, we have been consulting with NZTA for some time. Clearly we now need to engage central government."
The statement quotes Horowhenua District Council chief executive David Clapperton saying his council is extremely concerned about NZTA's backtracking.
"There is a mounting furore in the Horowhenua community, in particular from those with land that is closely affected," said Clapperton.
"Not only have livelihoods continued to be put on hold, the changing variables makes it difficult for council to make long-term plans for the benefit of our district."
Whanganui mayor Hamish McDouall said O2NL is a significant piece in the state highway system, linking Wellington to the Central North Island and beyond.
"Traffic issues and constraints in this area will only be exaggerated once the Transmission Gully expressway is opened next year," said McDouall.
"Fast, efficient and safe roading networks is vital for not just our region's economy but for the rest of the country."
Smith said the Horizons Region is uniquely placed in the centre of the lower North Island and has strategic connections north, south, east and west.
"As a region, we want to ensure central government and local government funding is optimised to benefit social, economy, cultural and environment outcomes for all."