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The party's caucus will assemble tomorrow to discuss how to be an effective opposition and plot its path to regain control of the front benches in 2023.
Collins told RNZ's Morning Report programme today: "It's important that we do look into everything that's gone on. And I think too, what went wrong and what went right and I think clearly, more went wrong than went right.
"I think it's important to not just look at the campaign itself but look at the last three years since the last time we had an election, I think that's really important and that's something the review will be doing."
The only example Collins would share about what went right during the campaign was the volunteer support the party received.
"Everything else I'm going to leave for the review."
Collins said having a full review conducted rather than "bits and pieces lopped off and discussed now" was important.
"This is a National party review, not something that we are going to be doing in the media."
Collins would not discuss her own view on how campaigning went.
"The review is a matter for the board and they are putting that all together ... that will be something that will be discussed with caucus."
Announcements regarding the review would be made by party president Peter Goodfellow, she said.