Simon Bridges has promised to give a controversial West Coast hydro-power scheme the green light, after the proposal was vetoed by the Minister for the Environment in August.
The scheme on the Waitaha River, which could have powered 12,000 homes, remains a polarising topic for West Coast residents.
Minister for the Environment David Parker declined Westpower's bid to build a dam structure on the basis it was too much of a threat to the character of the near-pristine area, and peoples' enjoyment of it.
The Waitaha River has stewardship status, meaning its conservation values are yet to be determined - and Mr Parker said he stood by his decision.
"I've had a lot of letters in support of this decision. I've also had some people that obviously disagree with it. But when you have a look at the photographs of the Morgan Gorge, which is an absolutely special bit of river, and you see the kayakers and hear their stories about how this is so important to them - and when you reflect on the fact that tourism is the biggest industry on the West Coast, I'm very comfortable that we've made the right decision," he said.
But the failed application hasn't sat well with all West Coasters.
On Sunday as people rallied against government policies they say unfairly disadvantage Westland, 5000 bumper stickers were distributed, declaring 'I Support the Waitaha Hydro Project'.
National MP Maureen Pugh described Mr Parker's decision as "probably one of the dumbest decisions that has been made," given Westland's plentiful supply of rainwater.
Opposition leader Simon Bridges said supporting the scheme was a "no brainer", when it comes to getting the West Coast economy going.
"National will, in the first hundred days, get the Waitaha power scheme on. There's simply no reason not to," he said.
That was welcomed by Westpower chief executive Rob Caldwell, who said he had been swamped with support for the scheme since it was declined.
He said it would provide security of supply benefits to South Westland and make a contribution to the government's target of 100 percent renewables by 2035.
West Coast Electric Power Trust chair Ian Hustwick, who printed the bumper stickers, was also thrilled.
He said he had never given up hope common sense would prevail and the scheme would go ahead.
"I never really been able to understand the rationale for it not being approved by the minister," he said.
"Listening to Simon Bridges and Nick Smith saying that if they get into government they're going to get this project moving is a very positive step. I was very pleased," he said.
But Mr Parker dismissed Bridge's promise as a "political stunt."
He said reversing the decision was a terrible move that would require overthrowing laws - and there were other hydro schemes elsewhere in the West Coast that already had consents, but were yet to be built.
His concerns were echoed by Jane Ruka of the Waitaha Grandmothers Executive Council, a group that stood staunchly against the project.
"It's a lovely place for the National Party to stand and use it as a hammer for their election purposes. But we're warning the National Party, do not approach Waitaha as your hammer," she said.
"As far as we're concerned and the environmentalists are concerned, the National government has never done anything to protect papatūānuku."
Forest and Bird, the Federated Mountain Clubs and kayakers group Whitewater New Zealand are also continuing to oppose the project.