More witnesses will face a robodebt royal commission to uncover what allowed the disastrous scheme to continue despite signs it was terminally flawed from the beginning.

The commission has heard from senior politicians and public servants, including former prime minister Scott Morrison, who cast blame on departments for not calling the issues to his attention.

Former director and assistant director of the Department of Social Services, Catherine Dalton and Anthony Bradford will face the commission on Friday.

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Dr Cassandra Goldie and Charmaine Crowe from the Australian Council of Social Services will also appear to help shed light on the impact felt by welfare recipients.

Also appearing at Friday’s hearing will be chief customer officer of Probe Group, Jarrod Kagan.

Karen Harfield, who was general manager for customer compliance at the Department of Human Services, appeared before the commission on Thursday.

She claimed some senior staff were resistant to overhauling the scheme due to planned government budget targets requiring a higher number of interventions.

Early proposals for the scheme identified potential savings to the federal budget of $1.2 billion by more efficiently identifying welfare discrepancies.

On Wednesday, Mr Morrison conceded the government had a strong desire to balance the budget and that it faced a hostile Senate, creating roadblocks for legislative reform.

Mr Morrison was asked by senior counsel assisting Justin Greggery KC if he appreciated that robodebt asked a lot of those on welfare who were in potentially vulnerable situations.

He replied that managing Australia’s social security system is a “very difficult task”.

“In seeking to ensure the integrity of the system that does of course put obligations on individuals who have been the recipients of payments. That’s unavoidable,” Mr Morrison.

-AAP