That is the question facing New Zealand's opposition National party as they head to September's election, uncertain on the leadership of alternative prime minister Simon Bridges.
National is the biggest party in parliament, polling 44% to Labour's 37% at the last election, but is serving in opposition after Ms Ardern cobbled together a coalition with minority partners on the right and left; NZ First and the Greens.
Ms Ardern, though not as popular in New Zealand as her international fame might suggest, is politically ascendant following her government's decisive response to COVID-19.
That popularity will be measured on Monday, when Newshub releases its "mind-blowing" first polling result since the arrival of the pandemic.
No one is expecting National and Mr Bridges to be in a winning position given COVID-19 has tilted the political playing field in favour of the incumbents.
But should National slip below a mid-30s threshold, the 43-year-old's leadership will be in focus.
"If we're polling in the high 30s, there's something we can work with. Then we're in the hunt," one shadow Cabinet member said.
"If it's lower, and it looks like people just aren't listening, we've got problems."
In considering a switch, National MPs will keep two election campaigns in their minds.
The first is the most recent, 2017, when Ms Ardern replaced Andrew Little as Labour leader just seven weeks out from the election, producing a "stardust" effect and a near 10-point bump in the polls.
The second is 2002, the last time National confronted a first-term Labour government, when the perennial powerhouse recorded its worst-ever result.
"If we're below 35%, well you can't win an election or form a government with those numbers," another shadow Cabinet member said.
"And if you're too low, people write you off. It's what happened in 2002 when people worked out National weren't going to win. So they went elsewhere to try and restrain Helen Clark's government."
Opposition members say no one is yet working numbers against Mr Bridges, waiting for those public polls.
That's also because there's no obvious replacement.
Judith Collins is a long-time leadership aspirant but hasn't been successful in previous ballots.
Another senior figure referred to Ms Collins as a "save the furniture" candidate.
Todd Muller and Mark Mitchell have also been touted as future leadership material, but have low nationwide profiles.
In the meantime, Mr Bridges will keep swinging at Ms Ardern's response and recovery plans for Covid-19.
Last week, he led a backlash against a 10-person cap at funerals, leading Ms Ardern to a rare policy backflip and extension to 50 people.
National is now championing a similar switch for religious gatherings, although Ms Ardern has ruled out a budge until a review of all conditions next week.
Mr Bridges declined to comment for this article.
