Fran O'Sullivan: Why Paula Bennett, not Judith Collins, is the one to watch

Paula Bennett has a strong opportunistic streak. Photo / Doug Sherring

Fifth-ranked Cabinet Minister Paula Bennett does not have Tim Groser's intellectual subtlety and flair.

It's hard to imagine - under any circumstances - Bennett quoting the 19th century Prussian General Von Moltke's comment that "no battle plan survives the first encounter with the enemy" as Groser did in a speech this year.

Nor does Bennett have the diplomatic nous to craft an international stratagem on climate change which Groser claims United States Special Envoy Todd Stern has acknowledged as a "realistic solution given the political realities that US negotiators have to take into account".

But Bennett does have a strong opportunistic streak.

She is the major winner from John Key's "surgical" Cabinet reshuffle.

Judith Collins is back in Cabinet. But she is not back on the front bench.

By awarding Bennett Groser's former Climate Change Issues portfolio - and symbolically pole-vaulting her further up National's informal succession ladder - Key has cleverly boxed in Collins' own ambitions for now.

But the Prime Minister is also taking a considerable political risk.

The climate change eco-system is full of players who see through the creative accounting which obscures NZ's inadequate response on climate change negotiations.

Key and Groser - like many Western political leaders - apply considerable bluff in this arena.

Bennett's own style is to smile guilelessly while she painstakingly flannels her way through news conferences or interviews on thorny issues such as Auckland's housing problems.

Like Key, she does not often lose her cool.

But National does face a credibility gap on climate change policies.

If National is serious it will manage through a transition to leveraging NZ's renewable energy resources to more effect. For instance, the Government is lagging when it comes to announcing programmes to convert vehicle fleets to electric power. This is an area where Energy Minister Simon Bridges and Bennett could use their combined clout to get change.

Where Bennett will be tested is with the Government's review of the emissions trading regime. The stated aim of this review is to see how the ETS can best support New Zealand in both meeting its climate change targets and transitioning to a low-emissions economy.

Groser will resign from Parliament on Monday when he returns from the Paris climate talks. He is expected to head to Washington early in the New Year - if not for a fleeting visit before Christmas - as the next NZ Ambassador to the United States.

The Washington embassy has been babysat by veteran diplomat Carl Worker since incumbent Mike Moore became ill.

But Worker - whose wife is head chef at a prime Waiheke restaurant - is understood to have told the Ministry of Foreign Affairs and Trade he could only do the role until mid-December. Hence, the need to get Groser into Washington fast, instead of leaving him in the trade portfolio until early next February when the Trans-Pacific Partnership is expected to be signed in Auckland by the TPP trade ministers.

There is a possibility that in the longer term Groser could take up an envoy's role in the climate arena on top of his ambassadorial duties. But he will be strongly focused on building the case for TPP (this still has to be voted in by the US Congress).

The Prime Minister faced another imperative.

The stumbling management of the Serco issue - combined with Collins' obvious profile building - also played a role in Key's decision to reshuffle the Cabinet now rather than wait until the New Year.

Collins is a tougher player than former Corrections Minister Sam Lotu-liga. Already she is laying some firm bottom lines.

But she remains a risk in the commercial arena.

She bluffed her way through the long-running Oravida scandal which would have sunk a lesser politician.

This - more than the "dirty politics" saga - is why some of the higher-placed National Cabinet members wanted to see the back of her after the 2014 election.

When Key threw Collins under the bus during the election campaign, she was already on the outer.

Some Cabinet members were fearful that the "dirty politics" saga would cost National the election.

So when a letter surfaced supposedly implicating Collins in a conspiracy to oust Adam Feeley as the chief executive of the Serious Fraud Office, the Prime Minister quickly seized on it to force her resignation from Cabinet.

Even after the election was settled - and after the Chisholm report which found no evidence to implicate Collins - some ministers continued to be openly antagonistic towards her. But in reality this has always been a difficult position to sustain for the longer term.

Not because of any supposed threat Collins might place to Key's leadership, but because the Prime Minister's team did not get off scot-free from the SIS leaks inquiry for which he himself had ministerial responsibility.