Labour MP David Parker has taken aim at National's evolving stance on how to handle COVID-19 at the border.
The party this week unveiled its border policy, which in addition to efforts already underway to keep the virus out, would introduce a dedicated border agency, require incoming travellers to have tested negative before boarding the plane, more testing in aged care facilities and compulsory contact tracing technology.
Under new leader Judith Collins, who has said the virus "simply would not be allowed in" on her watch, National has been less willing to embrace risky ideas, such as letting international students come into the country and have universities manage their 14 days of self-isolation, rather than the army and Government.
The party repeatedly pushed for the March-April lockdown levels to be lifted well ahead of what the Government was comfortable with, and as recently as last month, National was calling for a travel bubble to be opened up with Australia - which is now struggling with an outbreak bigger than what it went through when the pandemic first hit.
"Simon, you were telling us to let in students, to open up the Australian bubble, to bring people in from China," Parker told National's Simon Bridges, who until June led the party.
"I think you've been all over the place here. You can't have it both ways. The good news is that we've largely kept COVID out."
He said opening up with Australia "would have been a disaster", and the Government had to repeatedly toughen up its controls at the border, following a number of escapes and the possibility a leak could be behind the new Auckland cluster of cases.
"We've seen how hard that is to do even for the Government, with all the resources of Government; the idea that universities could do that by themselves is just ridiculous."
Bridges in response said the only reason National's ideas can't be implemented is because of the lack of confidence in the border system to keep the virus out.
"If you'd done the things that reasonable New Zealanders would have expected - like tested everyone at the borders, like had effective quarantining, like tested workers in New Zealand, we perhaps could be doing some sensible, nimble things right now to make sure we actually save our economy as well.
"It's not my fault, buddy, that you didn't do those things over the 100 or so days. You're all patting yourselves on the back, congratulating each other, saying how things were perfect - and they weren't."
New Zealand had no detected cases of community transmission for 102 days before the recent cluster. The Government is confident the outbreak is under control, with no exponential rise in the number of confirmed cases since Auckland went into alert level 3 lockdown and almost every detected infection being traced back to the cluster.
"We've been doing better than virtually anyone else in the world," said Parker.
"We've brought more than 40,000 people across the border. We've had this one issue of this new cluster - we haven't been able to trace that anywhere, actually. It may not have come through the managed isolation, we really don't know where it's come from.
"We have ramped up our response throughout - it hasn't all been perfect, but it gets better by the day. Since this cluster broke out we've tested over 100,000 New Zelanders. A few months back, we couldn't have done that over many months. I think most people realise that this is incredibly difficult."
The Government this week appointed a team to go over the existing border response to see how it could be improved.
"We have a task, we'll apply our minds to the task and get it done as soon as we can and then move on," said Sir Brian Roche, one of team's leaders. "I don't think this is a policing exercise, it's not a fault-finding exercise."