Simon Bridges has accused Labour MP David Parker of "sounding like The Donald" for saying a vaccine for COVID-19 will arrive soon.
US President Donald Trump has been talking up hopes of a vaccine arriving before the US election on November 3, claiming - without evidence - officials have been delaying it to hurt him politically.
After an unprecedented global effort, 11 potential vaccines have reached phase 3 clinical trials. Most experts believe the first deemed both safe and effective could possibly roll out by the end of the year, or possibly next year - if that happens, it would be the quickest vaccine development in history.
Former National leader Bridges and Parker were discussing New Zealand's coronavirus strategy on The AM Show on Friday morning when host Duncan Garner suggested our strategy of elimination could see us isolated from the rest of the world for years to come.
"No, no no. We won't," insisted Parker. "We're more than halfway through this, I think, before a vaccine. The vaccine's closer by the day."
"You're sounding surprisingly like The Donald," said Bridges, using a name popular with the controversial President's supporters.
Parker was quick to point out he's predicting a mid-2021 date for the vaccine, not mid-October.
New Zealand's strategy of not tolerating any community transmission of the virus has been praised by the World Health Organization and this week by Anthony Fauci, the top US infectious diseases expert.
But it does make opening travel bubbles with other countries difficult. Australia looks set to open the door to Kiwis, but the reverse isn't likely anytime soon.
"It's easy from their angle, isn't it?" said Parker. "We've got no community transmission in New Zealand so there's no COVID to catch here. But there's COVID to catch in Australia... You've seen how hard it was to squash the resurgence that we had with that cluster in Auckland. We don't want that to happen again."
Australia's latest outbreak peaked in early August, and was centred on the state of Victoria.
"I think David's forgetting that actually Australia is made up of states," said Bridges. "If you take South Australia... there have only been four deaths from this. You're talking low to no transmission in that state. On that basis, if there are safe processes, why wouldn't we explore that and start looking?"
South Australia has no current cases of the disease. Parker said the Government has told Australia it would be happy to open the border to Australians on a state-by-state basis, but Scott Morrison's federal government is insisting it be countrywide.
"Once community transmission is under control then we'll do it, but not if it's not safe because they've still got community transmission."
Garner asked Parker if the Government had a 'plan B'. Parker took that as a suggestion New Zealand adopts the strategy put forward by the controversial 'Plan B' group, which has advocated against lockdowns and wearing masks.
"If you mean should we open the borders to COVID, no we're not ready to do that. If there was no vaccine in years to come and COVID was ravaging the world, some of those difficult decisions have to be revisited - but we don't have to revisit them now."
Bridges said it was unlikely the Government hadn't formulated a 'plan B' of its own, accusing Parker of not wanting to frighten voters ahead of the election.
"I would be surprised if you guys don't - I just think you're not sharing them with New Zealanders because you've got this 'say nothing, do nothing, hope on Jacindamania' right up until election day."