He should also control his temper and demonstrate maturity as a leader.

These are the messages from public sector experts as the newly installed Prime Minister calls in senior mandarins for briefings.

Until Mr Rudd unveils his new ministry - which could be as early as Friday - the hiatus period of uncertainty will continue for the many public servants who do not know who their new minister will be.

The nadir of Mr Rudd's former turbulent time in dealing with public servants was his young office staff telling senior bureaucrats how to do their job.

Public servants will be watching carefully as Mr Rudd promises to reform, according to Stephen Bartos, governance expert with ACIL Allen Consulting.

''The early signals from Kevin Rudd will be important, such as - has he got a more mature office?'' he said.

''One of the reasons relations with the public service went off the rails a little bit was because there were 20-year-olds telling public servants of 40 years' standing how to do their jobs.

''So if Kevin Rudd sets the right tone by having a more mature office and a more measured pace in his relations with the public service, that'll be the signal that things have changed.''

Mr Bartos said there was uncertainty in the public service about the beginning of the caretaker period, which was due to begin in August.

Professor John Uhr, from the ANU's Crawford School of Public Policy, said: ''Those who worked well with Rudd will welcome the return and those who found things difficult when Rudd was Prime Minister might be anxious about whether Rudd's stated claim to have improved really has a strong evidence base for them.

''The biggest area where Rudd really needs to show he has matured as a leader is in COAG and federalism because so much of what any prime minister does is negotiate arrangements with the states.

''Rudd, like lots of prime ministers, found he does not have enough time to do detailed negotiations.

''I think he has to put more time aside and put officials into the right mood to be constructive negotiators.

''Potentially we've got a second opportunity for an experienced Prime Minister to learn how to manage federalism differently, so that's a real bonus if there is some improvement on display there.

''Even between now and the election there is the potential for a lot of constructive work that can be done through negotiated shared leadership.''

Professor Uhr said the Department of Prime Minister and Cabinet would be expected to manage administrative reforms such as reshaping large portfolios.

''I expect Prime Minister and Cabinet would be the one that would have a bit of sweat on their hands about how to shape up public administration,'' he said.

Mr Rudd would have to moderate unrealistic expectations about reform such as education, Professor Uhr said.

''So too with disability reform - the package was heroically pitched by the former prime minister.

''You can imagine the expectations of lots of citizens might be unrealistically high, that disability can be more properly managed tomorrow rather than the day after or the day after that.''