National MP Erica Stanford says the party's resigned Taieri candidate Stephen Jack sharing a poem that compared Jacinda Ardern to Adolf Hitler was unacceptable.
Jack resigned last night after Stuff reported he had re-posted a poem on Facebook in 2021, comparing the former prime minister to Hitler.
Stanford told Morning Report the then-prime minister deserved some respect.
"Making disparaging comments about the prime minister like that is not acceptable," she said.
"It's disrespectful. No matter what you think of Jacinda Ardern, she was our prime minister and she deserved some respect."
On Sunday it was reported by Stuff that Jack had also re-posted a sexist joke in 2020.
National's deputy leader Nicola Willis labelled that joke "disgusting" - and warned a repeat incident may trigger the party's disciplinary code.
Stanford said she had not met Jack and could not comment on whether the party's candidate selection panel had seen his comments.
"I don't know very much about this candidate, I've never met him, I only heard the news, as you probably did, break last night."
She said the party had acknowledged after the last few years that its processes for selecting candidates "weren't as robust as they could be" and it had been addressing that.
"I know the board have been going through every candidate ... even the existing MPs they went through, and made sure that the process was robust."
A National Party spokesperson told RNZ on Wednesday night via email that the party would open selection for another candidate for the seat in due course.