Prime Minister John Key said he would be surprised if the government did not help with rising costs should the Ruataniwha Dam project make it through legislative and local government challenges.

The Department of Conservation is seeking leave to appeal to the Supreme Court after the Court of Appeal stopped a land-swap to create the reservoir to irrigate 25,000ha of drought-prone farming and cropping land in Central Hawke's Bay.

Hawke's Bay Regional Council is driving the scheme but an anti-dam majority of councillors recently elected are stalling the project.

Mr Key said the area was a very important food bowl for New Zealand "and every so often there is a drought" costing millions of dollars.

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"In terms of jobs and just peace of mind, I think it is important," he said.

"Obviously there are environmental issues and they need to be considered, but it always struck us that the land swap that they were proposing was quite a sensible way through."

When asked if the government would help top up the scheme - construction costs were calculated during a construction slump in New Zealand and have risen considerably - he said it was likely.

He said there was a lot of money in the Ministry for Primary Industries' Irrigation Acceleration Fund "and we are not spending it as fast as we want to, because we are having to deal with these sorts of issues with the Ruataniwha".

"I find it very difficult to believe there wouldn't be some cash. That is the purpose of having the fund and it is quite big."

An upbeat Mr Key made the comments yesterday after meeting Havelock North businesspeople following a visit to Progressive Meats.

Tukituki MP Craig Foss said Mr Key's security staff kept a sharp eye on the many sharp knives in the boning room.

Mr Key's Chief of Staff Wayne Eagleson said the PM's primary reason for visiting Hawke's Bay was the Hawke's Bay Wine Auction tonight, which supports Cranford Hospice.

Mr Key said the auction was "famous" and he was well briefed on the event by former Napier MP Chris Tremain.

"He's the auctioneer tomorrow - is that the story?" Mr Key asked Mr Foss.

"Yes he is and he is quite good at getting money out of the PM," Mr Foss replied.

The Prime Minister promised to make a purchase.

On government legislation thwarting Hastings Districts' declaration of it being GE free, he said rules should be uniform and a national debate needed.

He said he was not surprised Donald Trump won the United States presidential race.

"I had a bet with my foreign policy advisor that he was going to win and then I kind of got cold feet about a month ago."

US elections usually had a 50 per cent voter turnout whereas New Zealand had 80 per cent.

"What Trump sort of knew was there was a really big group of people who are massively disaffected but who have never bothered to vote.

"The question was could he get them to turn out."

He quoted election commentators.

"He may not be the best messenger Batty but he had the right to message."

Another quote was: "The media took him literally and they didn't taken seriously and the voters took seriously but didn't take him literally."

He said he was confident Mr Trump would be pragmatic in his new role.

A populist movement in New Zealand was unlikely because of strong economic growth, stronger citizen engagement with government and any protest vote already went to Winston Peters.