While the opposition has long criticised the government's reliance on outsourced work, Mr Chalmers said changes his party would make wouldn't result in turbulent times for public servants and contractors.

"We're not in the business of tearing up contracts," he said.

"We need to make sure that any changes we make are responsible and defensible, but in time we do want to see a greater proportion of the workforce as public servants and a lesser proportion, or less money, spent on contractors and consultants and labour hire, which can cost the Commonwealth more money without necessarily getting a better outcome."

While the opposition has committed to removing the cap on public servant staff levels if it wins government, spending would still be capped and consultants brought in when needed.

"There will always be a mixed model, there will always be the need for external expert advice or to manage big fluctuations in staffing needs, but our view is that the pendulum has swung far too far and we need to start addressing it."

In a departure from previous elections, where Labor had made commitments to keep departmental secretaries if it won government, Mr Chalmers would say only that the process was for the prime minister of the day, on the advice of the secretary of Prime Minister and Cabinet and others.

Asked specifically about Treasury secretary Phil Gaetjens, who had been chief of staff to Scott Morrison and former treasurer Peter Costello, Mr Chalmers was non-committal.

"In the case of the Treasury secretary, Mr Gaetjens, Chris Bowen has made his views on that fairly clear. At the end of the day if Labor were to win office that would be a conversation between Bill Shorten, Chris Bowen and the head of the public service. But Chris has made it clear that he would find it difficult to work with Mr Gaetjens and that's not a matter for me, that's a matter for him."

While both Labor and the main public service union have savaged the government's approach to bargaining, Mr Chalmers gave little indication of how it would change under Labor, or whether the cap on pay rises that could be offered during bargaining would be lifted.

"We're still working through those issues, we're not ready to make public commentary on them. It involves my colleague [Labor workplace relations spokesman] Brendan O'Connor as well, and discussions with the various stakeholders as well, but we haven't issued a public position on that yet - we need to take some more advice and consult more widely."

Labor's campaign spokesman described his vision for public sector reform in two phases, the first a "triage" and the second to institute the principle of five "betters".

"The triage from our point of view is to deal with the ASL cap, to put on 1200 additional Department of Human Services staff, to cancel the last remaining year of the efficiency dividend, and to get more value for money by shaving spending on contractors, consultants and labour hire."

Mr Chalmers said the party's decision-making, if it were in government, would be guided by five principles.

"We're looking for five things: we want better services for people, we want better advice to government, we want better value for money, we want better co-ordination between agencies and with ministers and we want better job satisfaction for public servants."