Labour's deputy leader Kelvin Davis has had his first taste of standing in for the prime minister. It did not go well.

OPINION: Labour has a problem.

For the last week, Kelvin Davis has been acting prime minister and it's been nothing short of a trainwreck.

While Prime Minister Jacinda Ardern and her deputy, Winston Peters, have been cutting deals and forging relationships on the international stage in Vietnam and the Philippines, Davis has been left back in New Zealand to handle the day-to-day business.

MONIQUE FORD/STUFF Where was Finance Minister Grant Robertson on Wednesday to help Acting Prime Minister Kelvin Davis with the curly finance questions?

Before embarking on this week-long mission, Davis was pretty cool and calm about the whole thing and even described the role as a "figurehead" position.

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ROBERT KITCHIN/STUFF When Prime Minister Jacinda Ardern is out of the country, there's a high chance Foreign Affairs Minister and deputy PM Winston Peters will be as well. That leaves Kelvin Davis in charge unless Labour accepts it needs to appoint someone else.

While that might be the case in some respects, there's still a rather large press contingent back home with plenty of questions – not to mention a stack of Opposition MPs dying to embarrass the Government at any opportunity.

In fairness to Davis, this is not all his fault. Questions need to be asked of Labour's advisers and senior ministers with enough experience to know better, as to why they sent him like a lamb to the slaughter this week.

Davis had already had a taste of what was to come at Question Time last Thursday.

In this column a week ago, I congratulated Davis for doing an excellent job of saying absolutely nothing, but nobody seriously thought that was a strategy Labour could keep up.

Roll on to Tuesday and Davis was back in the House facing Opposition Leader Bill English on statistical steroids as he did what he does best – stringing together sentences with enough jargon and numbers to make a Treasury report look like child's play.

National worked out a long time ago that Davis was the weak link in the Labour leadership team and the party is in overdrive finding every way possible to expose that.

Every question Davis had thrown at him on Tuesday was answered first in muffled tones by ministers Phil Twyford, Chris Hipkins and Grant Robertson. Davis then stood up and repeated the answers.

The first and second time could have been written off as them helping him get started but it was just absurd when it continued for the entire stretch of supplementary questions.

The ministers didn't even try to hide the fact they were doing it and Davis blatantly looked to them every time before rising to his feet.

It was like a seriously bizarre game of Chinese whispers that started at Twyford and ran along the front bench until the message was received by Davis.

Wednesday arrived. It was a new day; perhaps a new strategy? Not a chance.

There were only two political stories anyone was interested in that day – North Korea and the Government's net debt target, economists having warned billions would need to be borrowed over the coming years.

As the media gathered on "the tiles", where ministers are questioned on their way into the House, Davis strode across the bridge toward journalists on his own.

Finance Minister Grant Robertson, who was always going to be stopped for questioning that day, had hit the tiles about 30 seconds ahead of Davis. Something wasn't right.

What doesn't make sense about this is Labour loves nothing more than to wheel out MPs to stand alongside their leader to nod and show a united front. It's a smart strategy – one it usually does better than National – but something went wrong on Wednesday.

Had they used Chinese whispers to deliver the message to Robertson that he needed to walk the media gauntlet with Davis to help with the curly finance questions, but by the time the message landed it had gone skew-whiff?

Davis got thrown to the pack and desperately tried to keep his head above water.

Asked what year Labour wanted to reduce net debt to 20 per cent of GDP by, Davis stumbled around before spluttering "over the economic cycle".

Unconvinced, the reporter asked again, yes, but what year?

Red-faced and out of his depth, Davis conceded he had lost and switched to straight-up honesty, saying, "I'm sorry, I don't know the answer to that".

This is a key policy of Labour's and, yes, it's hard to remember lots of numbers and years but Davis was presumably well prepped on this topic and still didn't get across the line.

Where was Robertson?

Things didn't get much better in Question Time. The Opposition had not one but three questions lined up for Davis to put him under pressure in a number of portfolios.

But that's not before he had made a clarification to the House, after saying the week before in answer to a question about the cost of additional police that "those costs have been finalised".

Actually, "those costs have yet to be finalised".

While it's clear Davis isn't a natural when it comes to the House and dealing with questions on the fly, that doesn't mean there aren't senior ministers who are.

Robertson and Hipkins are both brilliant performers in the House, who can think on their feet.

The problem Labour has is that Robertson is the obvious person to be acting prime minister and actually there's no reason he can't be.

Peters is barely ever going to fill that role because chances are if Jacinda Ardern's out of the country, then, as foreign affairs minister, he's likely to be too.

Labour needs Davis to remain the party's deputy leader because his promotion to that role ahead of the election was a smart one and no doubt went a long way to helping it win all seven Māori seats.

But the party can't sustain the cringeworthy chaos on display of late and it needs a new plan by the time Ardern and Peters jet out of the country again.

Ardern can appoint Robertson in the acting role and keep Davis as deputy leader. It's messy, but not as messy as what was on display last week.

Failing that, the Government can choose who answers questions in the House on behalf of the prime minister.

If Ardern is away, then Robertson needs to be nominated as acting leader for the purposes of the House at least. It doesn't solve the issue of press conferences but it gets halfway there.

Labour needs to accept that the status quo is not working. It has options. The clock is ticking on finding an alternative.

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