Power Play - The phones are running hot in the National Party caucus as MPs frantically try to figure out whether to replace Simon Bridges as leader after this week's massive backlash.

Photo: Pool / Getty Images

Minutes after Prime Minister Jacinda Ardern announced the lockdown would continue for another week, Bridges shot out a media release accusing the government of not having "done the groundwork" despite the rest of the country having done such a great job.

The shutdown has been bookmarked by two serious cases of misjudgement: the first was his' "beneficiaries baked in" outburst in Parliament, and now this latest one.

Bridges' Facebook page exploded with people objecting to its tone; a strong theme among the thousands of posts which even traditional National supporters believed the government had done a good job. It's far from a scientific gauge for public sentiment but is certainly a canary in the mine, especially for MPs.

The actual substance of his comments was valid: there are still questions around the future capacity of contact tracing, whether those on the frontline are getting the personal protective gear where and when they need it, and the consequences of the extended lockdown for small business owners.

All of this could have been said - as it has been for several weeks by National MPs - without the political overtone that sparked such outrage. Under usual circumstances his media release would have been tame and uncontroversial; the misjudgement occurred in the failure to register the public distaste of any suggestion New Zealand has not done well and a heightened reluctance to hear the government criticised.

MPs spoken to by RNZ were both dismayed and alarmed by the tsunami of negative public reaction.

That's catapulted him into a place where once again his leadership is under threat. We've seen this before though; he's seen off challenges in the toughest of times and will fight hard to do so again.

No active challenge yet but if MPs decide to move it could happen quickly - Bridges is helped by the fact MPs are in lockdown around the country rather than being able to congregate at Parliament; the longer the full caucus is unable to return to the capital, the better for him.

About half of National's MPs could be back when Parliament resumes next week but it will some time before they're all back.

Given the stakes and proximity to the election a change though could be quick and brutal - a vote or solid demonstration of no confidence and a new leadership team installed.

The only credible contenders are Judith Collins and a combination of Todd Muller and Nikki Kaye.

Collins has had a tilt before so she'd want to see solid majority numbers before making a move. She's experienced and popular with the base; a stand out performer against the government but has history with some of the senior and more long serving members of the caucus.

Muller is low profile but has been working hard away from Parliament as agriculture spokesperson, a key portfolio for heartland National - he's smart and affable but does he have the stomach for a caucus throwdown? Kaye is a former Cabinet minister, a fierce campaigner (who beat Ardern twice in Auckland Central) with a good public profile, appealing to the more urban and socially liberal National voter.

While this has all reignited grumbles among MPs, there have been ongoing niggles including the view caucus business is controlled by a very tight team around Bridges. MPs say that includes detailed information around internal polling, which even on the party vote hasn't been made freely available in the last month or so.

One school of thought would be to let Bridges contest the election - if National wins all good, if not roll him.

The problem though for a large chunk of the caucus is that could bring their political careers to an abrupt end if they're in a marginal seat, or have a low list placing. The other consideration is the imminent arrival of Chris Luxon into the caucus, if - as expected - he takes Botany, there may not be a clear run at the leadership for those who fancy their chances now.

Once the electorate stops listening to what Bridges has to say he becomes irrelevant as Opposition leader and risks taking his party with him. National is relying on its ability to sell itself as the most credible economic manager in the Covid fallout but that in itself relies on maintaining its brand and public trust.

The dilemma for MPs is clear.

Some may be looking back at 2017 when Andrew Little made way for Jacinda Ardern and thinking a repeat on their side might be possible, but the dynamics are different including Bridges himself - he's a scrapper and won't go away without a fight. A public view that the party is more focused on itself than the Covid crisis would also not play well.

But those who fear Bridges' leadership could end their time as an MP may well think it's worth the roll of the dice.