Christopher Luxon says he has never met with the man that was - until Wednesday - National's candidate for Taieri, and didn't call or message him when he was selected.
The party leader said it was a "good thing" that Stephen Jack had resigned after controversial social media posts, including one comparing the former Prime Minister to Adolf Hitler, emerged.
However, Luxon still believes that, despite the scandal and other issues raised about National candidates, the party's selection process has been "strengthened".
Jack resigned as National's candidate in the South Island electorate on Wednesday night after it came to light that in 2021 he reposted a poem on his personal Facebook account likening Jacinda Ardern to Hitler.
The candidate earlier this week removed a comment he made online saying, "I like my Covid like I like my women. 19. And easy to spread". That remark was labelled "crass" by Luxon.
Speaking to media for the first time since Jack's resignation, Luxon on Thursday said it was the right decision for him to stand down.
"From my perspective, as a father of a 21-year-old daughter, I found those comments crass and offensive and sexist. It's a good thing that he's resigned," Luxon said.
He said he hadn't met Jack himself and hadn't texted or called him when he was selected. Jack was selected at the end of March.
Asked if the selection process had let him down, Luxon said National's process has "strengthened incredibly".
"I am incredibly proud of the candidates that we've actually been delivering into this election," Luxon said.
"What we've got is candidates that are emerging that have great diversity, coming with a diverse set of experiences, lots of new skills that they can bring to our caucus team."
He said there are things that the party will learn from this, but "the most important thing is that he's resigned".
"It's up for our party with the selection of candidates…I'm proud of the work that we've done over the last year to make sure we actually unearth talent that wants to come in and actually do these jobs as Members of Parliament and bring a unique set of skills and experiences to the job."
Luxon said "not all candidates are going to be perfect" and some will have things in their past that they want to declare.
"I think we've ended up with a much more robust process and I think you're seeing that, I mean, we've got really high quality calibre candidates coming into the National Party for 2023."
National's had several issues with candidates - and MPs - in the recent past.
Newshub revealed earlier this month that National's candidate for Maungakiekie, Greg Fleming, compared civil unions to polygamy and incest during the civil unions debate. He admitted his comments "weren't helpful" and he wouldn't make them again.
Last year, it emerged that newly-elected Tauranga MP Sam Uffindell had beaten a younger student while he was at high school.
