Labour Party finance spokesperson Grant Robertson has slammed National as "not fit to govern" after a leaked email revealed a rift in the party.
Lee called it a "highly problematic idea", a "nightmare" and "another working group", and said bypassing her was "incredibly poor form and displays a shockingly bad example of poor culture", while another National Party member said Collins was consistently "making up policy on the hoof" and creating division.
In a statement today, Robertson said it shows "National are a chaotic shambles that can't be trusted to run the country at such a critical time in our Covid recovery".
"This email seems to prove the rumours of a campaign in chaos. National have churned through three leaders in the space of three months, faces an exodus of 19 experienced MPs like Amy Adams, Nikki Kaye and Paula Bennett at the election and according to this email are still infighting.
"National clearly are no longer the party of John Key and Bill English, and their credentials on economic management are shot. They are now a divided party who pose a real threat to our economic recovery if they were elected."
However, Collins denied a division in her party when questioned by media today.
Collins said "one of the joys" of being party leader was that she makes the decisions.
"I'm not making up policy on the hoof, so number one leaders do make decisions, that's part of leadership," she said.
"During campaigns, sometimes the leader just has to go out and make that announcement and that's the way it works.
"I understand that the MP involved, it's her first time campaigning as an MP. The thing is that that's what leaders do, Miss Ardern calls it the captain's call, I call it the leader's call."
Collins said "obviously she [Lee] is wrong" but that she was now "focused on the party vote and her seat".
"I'm very happy with the fact we have a very good robust process and in the campaign, the campaign team makes that decision. I am very happy with that decision, I made the call and Aucklanders are telling me they are delighted with a review of Auckland Council," Collins said.
However, responding to claims from another MP that this was a pattern of behaviour in National, Collins said "I'm sure he'll apologise" but then wouldn't specify who "he" was when probed.
"I'm sure you know," she told reporters.
"The issue has been dealt with, I have already dealt with it and I am very aware of the situation that some people get under stress during campaigns, personally I don't, I love them."
When asked about an MP liking a tweet against her, Collins brushed it aside saying "sometimes people's fingers slip".
"The National Party has had to deal with some very difficult issues this year and I've dealt with those very decisively."
Labour leader Jacinda Ardern told media today that "internal issues" were not what New Zealanders want from political parties.
"No matter what, what it does amount to are obviously internal issues there and look, that is a matter for National. What we're going to remain focused on is that plan for recovery for New Zealand, that's what new Zealand needs right now."
When asked if Collins was making policy on a hoof, she said "I'd certainly say you can't afford that from any political party right now".