Labor leader Bill Shorten believes Emma Husar has been treated unfairly, as the disgruntled western Sydney MP weighs up leaving the party to sit on the cross bench.
Ms Husar announced in August she would not contest the next election after controversy surrounding bullying allegations.
But she's since changed her mind, launching vocal criticism of the party's treatment of her and hinting she may sit as an independent.
"Emma has not confirmed that she's moving to the cross bench and I'm not going to go into private conversations," Mr Shorten told reporters in Melbourne on Sunday.
"I think some of the treatment she's received has been unfair but she's made a decision not to run."
Labor has preselected former NSW minister Diane Beamer for Ms Husar's seat of Lindsay.
Last week, Ms Husar accused senior Labor figures of making her position in the party untenable through their lack of public support.
In August, Labor's internal investigation cleared Ms Husar of allegations of lewd conduct and sexual harassment of employees, finding there was no need for her to resign.
However, the report did find she behaved unreasonably towards staff and there were grounds for further investigation into the alleged misuse of entitlements.
Ms Husar is in the midst of a defamation lawsuit against the media outlet that revealed the allegations made against her during the investigation.
The MP launched legal action against BuzzFeed and journalist Alice Workman over their story from early August.
Australian Associated Press