Key Points:

He's sleek, affable, has charisma and natural political instincts but lacks experience and gravitas yet has such confidence it's both impressive and a little unnerving.

And while people no longer ask who John Key is and clearly seem to like him, they remain unsure what he stands for and where he would take the National Party. This smooth operator who appears about to take over the party is something of a mystery man.

He will be pitched as the great Kiwi success story - the now familiar yarn of the rags-to-riches state-house boy turned millionaire. It's a bonus to be able to flaunt the state-house factor in Labour's face. And it acts as a counter to the inevitable accusation that he's Parliament's richest MP - estimated worth more than $50 million - and is a fat cat who can't understand how the rest of us live.

But as one of his colleagues notes, the former high-flying investment banker is in many ways still a blank canvas when it comes to a political persona - and that could either be an advantage or a disadvantage.

The expectations will be huge.

After seven years in opposition and with one of the biggest caucuses in recent years, the party will not be forgiving of another defeat.

Key's absence of self-doubt, his ambition and, critically, his poll ratings have convinced the bulk of his colleagues he is worth taking a chance on.

Bill English is highly rated and a much more experienced politician. He's networked extensively at all levels of the party since recovering from losing the leadership, ensuring widespread influence and knowledge of what's going on. He's more accomplished than Key in the House and - again unlike Key - has a demonstrated ability to deal commandingly with a wide range of policy issues.

Like Key he is passionate about what he does, although similarly perhaps doesn't exactly impassion voters.

But he's failed to charm the public - rating just 0.8 as preferred Prime Minister in this week's Herald poll of 750 Aucklanders - while Key with 17.3 per cent clearly has.

It was a fairly startling result for a non-party leader who's been keeping a low profile in recent months - precisely to avoid suspicion he was campaigning for his boss's job - and is ultimately likely to be the factor which convinces colleagues to give him, rather than English, the job.

Because of the respect in which English is held and the desire to avoid a bloodbath, MPs will, however, promise to seriously consider him.

At least some firm English supporters - variously estimated at between six and 12 - are trying to convince him to run for the deputy's job, and while he has privately expressed an aversion to this, he stressed yesterday he had not ruled it out and may be warming to the idea, perhaps as a double act with a finance role, similar to that of Michael Cullen for Labour.

English supporter Simon Power is otherwise seen as the camp's alternate contender for deputy.

While deputy leader Gerry Brownlee appears to have solid support for keeping his job, the desire to appease the English bloc may yet complicate that vote.

Since announcing he would contest the leadership, Key has been close to paranoid about appearing to have it in the bag, refusing all media interviews.

There's sometimes a fine line between confidence and arrogance and it's something he's well aware of.

He once said of financial trading, "It's all about pattern recognition and intuition and confidence. You need to be confident, but not cocky."

While some senior colleagues have considered him cocky at times, wading into others' policy areas in his first three years, he is said to have impressed by taking the growlings with a smile.

He similarly worked to repair rifts when he was publicly attacked by an unnamed senior MP - now in his camp - for apparent self-promotion at the beginning of the year.

A former employee who worked for him at Bankers Trust said, "John seems to have the knack of making you feel good when he's making more money than you are. He keeps you in the equation."

But convincing those senior National MPs to actually treat him as chairman of the board will take some work. The right deputy will be crucial to ensuring he has the necessary back-up.

It seems unlikely Key will risk rocking the boat by rushing significant changes to portfolios areas.

Brash might get education - particularly if English gets finance - or economic development, but Key is considered unlikely to give Brash a seat on the front bench.

It will be interesting to see which staff he retains - particularly whether he keeps Peter Keenan, Brash's far-right (yet politically pragmatic) policy adviser and speechwriter whose frank and cynical emails - including a reference to core supporters as "almost barking mad" - make fascinating reading in Nicky Hager's book The Hollow Men.

The book provides a useful checklist of what Key cannot afford to do. Brash's heavy reliance on a cabal of right-wing outsiders, who were determined to seize control of the party's strategy was "Don's fatal flaw" one senior MP said yesterday. "It was debilitating for caucus members because you don't know who you're dealing with."

The fight-back served to unite senior MPs such as English, Brownlee and Murray McCully in one respect, although the former was among a number of MPs who have bitterly resented McCully's strong day-to-day influence over Brash.

An early 2005 English email to Brash in the book reveals just how tense things have been in the caucus.

He accused McCully of burning off anyone who got in his way and Brownlee of looking after his own interests.

"You need to know now that experienced people you have will NOT work in a government run by McCully. I and others will not tolerate him exercising the same influence he does now."

McCully, already friendly with Key, yet sensitive about his Machiavellian reputation, is likely to pre-empt any attempts to prevent him from becoming Key's right-hand strategist by expressing a desire to step aside from the role he performed for Brash.

He did the same to Brash following criticism after the election, but was pulled back soon afterwards.

Just who Key will turn to is unclear; it appears he does not have a coterie of friends and advisers in caucus - which again could work for or against him.

Lockwood Smith, Wayne Mapp, Craig Foss, Maurice Williamson and Mark Blumsky are amongst those who have been agitating for a leadership change in his favour, but they're not seen as a tight Key unit and he'll need more heavyweight help.

Again, the deputy will help play a crucial role in uniting the different strands in the caucus, which is one reason English might strategically be preferable from Key's perspective.

It would at the same time prevent him from running a destabilising campaign, and he's also stronger on organisational detail than Brownlee.

Yet it does appear Key and Brownlee have at least done an unofficial deal and, unsurprisingly, Key and English would have trust issues.

The English camp has been white-anting Key for failing to decisively seize the leadership in recent months, in an attempt to portray him as politically impotent.

In fact, Key has known Brash planned to stand down after Christmas, although for how long isn't clear.

While Brash said on Thursday he had been considering resigning for three weeks, sources say he has, in fact, been pondering it for several months.

Key had no reason to jump him. Instead he's been swotting up on the wide range of policy areas he's set to be quizzed on.

He's considered a pragmatist and reasonably centrist - certainly much more so than Brash.

Former Brash chief of staff Richard Long admitted this week Brash was often outvoted by the caucus - and warned by staff - on policy, where they wanted to rein in his extremism.

In other instances it was due to his lack of political instinct.

Hager's book reveals startling (for National) examples of Brash's approach to policy in his draft Orewa speech on welfare.

In one part he wrote, "Children born to young women of 17 and under should be made available for adoption or supported by the mother's family."

He also proffered "a possibly outrageous suggestion that we provide free contraception to women between the ages of 16 and 30 on a doctor's prescription, on the grounds that it might appeal to women and could well be 'self-funding' ... is this a totally stupid idea?"

Because his political instincts are better than Brash's it seems unlikely Key will repeat the same mistakes - his common sense approach to problem-solving is often noted - yet his similar economic background may present some obstacles.

A key test will be his ability to talk with sophistication on the big social issues like the Treaty, which alienated Brash from middle voters.

Most of the caucus want at least a change in tone on the issue and Key is likely to lead the charge by taking a more aspirational line.

Taking a leaf out of the British Tories' book, he privately believes Brash has campaigned too negatively, including when talking about the dire economic gap between Australia and New Zealand.

The difference was evident in his economic vision for the next 25 years speech given at this year's party conference, in which he concluded: "I have to say, I am optimistic about the future of New Zealand.

"I think we can look forward to a vibrant economy and a vibrant future ... where people want to stay, work, and raise their families."

Key is considered relatively socially liberal by his colleagues, yet voted against the Civil Union bill and favoured a split drinking age - raising the purchasing age to 20 - when the issue was recently debated.

A colleague said his stance on some conscience issues reflected his conservative electorate, rather than his own private views.

He was less than upfront when quizzed about whether he believed in God on Agenda in April.

"That's an interesting question.

"Do I believe in God? I don't believe in life after death."

Asked again he said: "Well I don't believe in life after death; I don't know."

Asked for a third time: "Well if you're asking me if I'm religious it depends how you define religion.

"I look at religion as doing the right thing; I don't define that as someone that goes to church necessarily on a Sunday.

"I mean I go to church a lot with the kids, but I wouldn't describe it as something that I ... I'm not a heavy believer; my mother was Jewish which technically makes me Jewish. Yeah, I probably see it in a slightly more relaxed way."

Which leaves us not much closer to knowing the real John Key - although it appears inevitable the picture on the canvas will soon begin to take shape.