Some of National's Hutt South MP Chris Bishop's election hoardings have been destroyed less than a day after they were put up.

Meanwhile in Auckland images of Jacinda Ardern have also been defaced with crude, sexist vandalism.

Bishop, who is National's infrastructures and transport spokesman, posted photos of the damaged billboards on his Facebook page.

Hutt South MP Chris Bishop's hoarding destroyed less than a day after it was put up. Photo / Supplied

"Gutting to see some dickhead(s) do this to our signs not even 24 hours after they were put up," he said.

One of the flattened billboards.

"Of course every other party's signs were left totally intact."

Bishop had two days ago just declared support for new National leader Judith Collins' massive $31 billion dollar plan to improve infrastructure in the upper half of the North Island.

Collins had also said a National government would repeal the Resource Management Act completely and replace it with new law.

Bishop said in an interview these were "pricey ... but worth it".

National wasn't the only political party to be targeted by vandals.

Images of Prime Minister Jacinda Ardern have been daubed with crude, sexist remarks in Auckland.

On Saturday Labour Party candidate for Northcote Shanan Halbert shared a photo of himself cleaning one of his defaced signs.

"I'm all up for people having their own opinions, and that is the absolute point of an election. But use your own signs to share your message," he said on Twitter.

Overnight several of the party's signs were targeted again.

On of the defaced Labour Party billboards.

"Our signs got hit again last night," Halbert wrote on Facebook.

"It's very sad for our volunteers who [do] the hard work to get these up. We have sightings of the vehicle so will pass this on to the police."

On of the defaced Labour Party billboards.