Former Liberal staffer Brittany Higgins is expected to make a formal complaint to police alleging she was raped by a colleague inside Parliament House.
Ms Higgins has signalled she will speak to police on Wednesday afternoon after going public with the sexual assault allegation last week.
Three more women have come forward saying they were also assaulted by the man.
Defence Minister Linda Reynolds has been under intense pressure to detail her response to the allegations in 2019 when she employed Ms Higgins.
She will front the National Press Club in Canberra to make a rare, pre-planned appearance to speak about her portfolio.
Senator Reynolds is expected to receive a barrage of questions about the incident after her speech, following days of parliamentary scrutiny.
On Tuesday, she referenced a second meeting with the Australian Federal Police for the first time.
She later backtracked, promising to check her records to confirm the sequence of events after she found out about the alleged rape.
Prime Minister Scott Morrison has also faced questions about when he found out about the incident but he insists it wasn’t until last week.
There are four inquiries into different aspects of the culture inside Parliament House, what the prime minister’s office knew about the allegations and complaints processes.