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