Why would anyone want to be prime minister? Why indeed?

It is a job that will almost certainly end in failure. Only one prime minister in the last 100 years has left office at the time of his own choosing: and Robert Menzies had been there for 16 years (and more than 18 years in all).

So my biography of Kevin Rudd had the same objective as my study of Malcolm Fraser 25 years ago: what does it take to be a prime minister? How do they meet the challenges, what are their strengths and weaknesses, how do they organise their time and set priorities to meet the multiple roles?

Consider the negatives. Everything you have ever said or done, back to student days and beyond, will be uncovered, analysed and interpreted in as malign a way as possible. Every motive will be challenged and questioned.

Your enemies will seek to undermine you. The press will hound you. And then you have to deal with the Opposition.

Very few people have actually achieved the office. Australia has had 28 prime ministers, but three of them were caretakers, in the position after a prime minister died while the party elected a new leader. Of the other 25, two won four terms, three had three terms and three had two terms. All the others had only the one.

They are remarkable just for getting there. Max Weber described politics as “the strong and slow boring of hard boards”. So it is, for years.

Yet fortunately there are those who aspire and conspire to achieve that height. In every first-year politics class there will be someone, often more than one, who dreams of being PM. They want to make a difference; they see the potential in national leadership.

But few are prepared for the decades of effort. They must work through the party to build support to stand and win a seat.

Gaining party leadership means copping abuse, insinuations and accusations. After all that, opposition leaders in a time of strong government are unlikely to become prime minister. They must have good timing and luck.

Only then can they try to lead, to meet the inevitably high expectations they have set themselves and that their supporters have of them. Nothing can really prepare a person for the pressures of the job.

Balancing the demands of power

Once in office, the demands on prime ministers are diverse and constant. Almost all struggle in their first term, as they shift from the opposition target, to pressure to get a positive daily headline to the government requirement to meet real challenges.

AAP/Ketut Karna

As one senior minister noted, as soon as he got into office, everything he said was taken seriously. Their worlds had changed.

Consider the expectations. Prime ministers must play a wide range of roles, every one of which can turn out to be crucial to their survival. They must fulfil many expectations or face excoriation and expulsion.

They must lead their party in parliament and in the electorate. They have to understand and balance the ambitions, stroke the egos, listen to complaints and thus retain their support. They cannot be ignored for ever. A prime minister needs a united party. If that requires compromise, then compromise will follow.

Despite being forced to compromise they must act as the principal advocate of government in the face of a constant news cycle and a media looking for stories about errors, disagreements, inadequate understandings of ambiguous circumstances, and on any topic the media chooses to raise. Prime ministers cannot say they don’t know too often. They are meant to know.

In addition, they must front the government in parliament. Question time is a daily cross-examination of the prime minister who gets the lion’s share of opposition questions. It is true they seldom answer them, but they still need to know what will come up. That takes time and briefing too.

Prime ministers and ministers take parliament very seriously. Besides prime ministers also have to worry about how to deal with the Senate, another story altogether. How blessed are New Zealand prime minsters who have to manage but a single house of parliament.

Because they are held responsible, they must oversee all government policy, whether presiding over cabinet or by taking the lead themselves in areas of strategic importance. Government policy needs to be coherent, practical and effective; it also needs to be timely. All policies will face opposition, be it climate change, education, pensions or budget cuts.

Prime ministers must also represent the nation in moments of national grief: floods, bushfires, military funerals. They must grieve and give condolences on behalf of the nation and be seen to be sincere.

EPA/Pornchai Kittiwongsakul

This is part of the duty to manage crises, whether economic catastrophe or national threat. Decisions must be made fast on the basis of available information. Sometimes governments cannot wait until they have all the information; they need to act quickly and have to trust their judgement. The criticisms come later. Only oppositions have the benefit of hindsight.

This representation also requires their involvement in international forums: the UN, G20, ASEAN, APEC. PMs face pressure to attend because they have the power to commit their countries on the spot if they think it necessary.

Somewhere within this maelstrom, a few attempt a family life.

To write about a prime minister all these roles need to be kept in balance. It is a glorious challenge that tests them all; not all cope. That is no surprise.

Their struggles need not be a cause for sympathy; they fought desperately for the role. But we can try to understand what they must do.

Rudd never reached the heights of which he dreamed, nor was he as muddled as his assassins have ought to portray him. So the book tries be the story of the man and the exploration of the position to which he rose, not once, but twice.

The author spent several years observing and talking to Rudd and the people around him in preparation for writing the biography, Kevin Rudd: Twice Prime Minister, published by MUP.