The chairperson of Greater Wellington Regional Council says the National Party will not get rid of the Let's Get Wellington Moving project, other than its name.
National says a lack of progress means the plan will be scrapped if the party is elected in October.
Simeon Brown told Morning Report his party wants to focus on the Mt Victoria Tunnel and Basin Reserve upgrade to improve traffic flows to the eastern suburbs.
But regional council chairperson Daran Ponter said those are two large projects already being planned under Let's Get Wellington Moving.
"I think it sounds dramatic, 'we're going to get rid of Let's Get Wellington Moving'. But it sounds like they're still going to deliver on those big-ticket items the administration committed to six-and-a-half-years ago."
Ponter said in terms of the other projects under Let's Get Wellington Moving, National needed to have a long-term answer to how people are going to get across the city.
He said if the programme falls apart, Wellington City Council and GWRC will continue to work on transport solutions for Wellingtonians.
"Some of the solutions we end up delivering may be clunkier than any of us would have liked."
His biggest concern is how those projects would be funded.
"The government is the biggest funder in this arrangement. That would be the bigger worry, rather than the programme collapsing, if the government said 'we're not going to provide nearly as much money as we did previously'.
"At that stage, I think Wellingtonians would be sitting straight up in their seats and wondering if they'd been short-changed by the government".
Mayoral opposition
In a statement, Wellington Mayor Tory Whanau said National's plan would do nothing to grow the city, make it more livable or tackle the climate crisis.
She said ditching light rail was a backwards step and urged National to speak to experts who had been supporting the project.
"Ramming through a four-lane highway and tunnel won't win the votes of Wellingtonians who have shown consistent support for light rail in the city.
"The light rail spine would create superb housing opportunities as future growth in the city ramps up.
"We need to unlock investment in the city, not dampen it with a flaccid vision".
Councillor Tamatha Paul - who is also the Green Party candidate for Wellington Central in the upcoming general election - told RNZ there would be disastrous consequences for the environment if the Let's Get Wellington Moving project was scrapped.
She said National's proposal went against what Wellingtonians voted for.
People wanted light rail, bus priority lanes, and improved pedestrian access, Paul said.
"What National is proposing is, 'Shall we just cut all the things that make our planet livable to just make it more convenient and save 10 seconds of your journey every day?'
"That's in spite of all the efforts we're making to take urgent climate action."
Paul said the last thing Wellington and the country needed was more roads and highways.