There are some clear choices to replace struggling Police Minister Poto Williams if Labour has any hope of regaining control of the law and order agenda.
Ardern needs one of her best ministers, the ones with political smarts, who can think on their feet, can manage problems in a disciplined and authoritative way, and know how to dampen controversy, not fuel it.
That narrows it down to three people: Megan Woods, Chris Hipkins and Michael Wood.
They are good managers of their portfolios and they are good in the House as Wood demonstrated today in response to questions about hiccups in feebates for cars.
Woods and Hipkins are already proven fix-it ministers, having previously taken on the jobs of ministers struggling in housing and in health.
And if they offer resistance on the basis of overwork, Ardern could do worse than enlisting former Police Minister Stuart Nash.
House performance does not matter much when things are going well. But when they are not, the House acts like a sub-woofer on a struggling minister. It accentuates flaws you didn't know were there, as Williams often illustrates.
Ardern's professed confidence in Williams on Monday is not evidence that she will keep her in the job. All Prime Ministers must profess confidence in their ministers until the day the change is made.
It was a gamble when Ardern put Williams in there at the start of the second term, but not because of her inexperience.
Plenty of competent Police Ministers had never been a minister previously when they got the job: George Hawkins, Judith Collins and Stuart Nash, for example.
And Poto Williams had been a minister for more than a year. Towards the end of Ardern's first term in Government, Williams was promoted in a reshuffle from Assistant Speaker to a Minister outside Cabinet, responsible for the Community and Voluntary Sector, as well as getting three associate ministerial roles.
The gamble Ardern took in giving Police to Williams was not because of her experience but because she was not a natural fit in a job.
In Labour or National, the Police portfolio has gone to people who are naturally hard-line law and order types.
Ardern clearly chose Williams precisely because she didn't fit the stereotype. Her expertise was in community health and welfare, and tackling family violence.
For a Government that was looking for a culture change in the Police, an appointment of a social justice advocate may have made sense symbolically instead of reappointing Nash.
And Ardern possibly thought it was a portfolio that did not require much political skill because it is at arm's length from operational matters.
But she did not foresee the dramatic changes in criminal offending, and the political flashpoint the portfolio has become where gang shootouts in broad daylight and aggravated robberies have become commonplace.
The political reality requires a rethink by Ardern.
Williams usually does okay in the first question on notice in the House and gives an adequately scripted reply. But after that, there is a sense of trepidation about how well she will go without notes - and it is usually a faltering performance as was the case today when questioned by National's Mark Mitchell.
National has been targeting Williams as a weak minister, despite the occasional suggestion from Speaker Trevor Mallard that it could be seen as sexist or racist.
It will be more intense next year when Act makes it a focus as well. It needs a proven performer.
For an issue that will be so potent in election year, Williams' staying put would be a big risk for Ardern, and she is almost certainly considering the alternatives.