Opposition Leader Bill Shorten will not be supporting MP Emma Husar in her bid to contest the next election on Labor's ticket, the ABC understands.
In August Ms Husar announced her intention to quit politics amid an investigation into claims of misconduct, including sexual harassment allegations that were later not upheld.
The first-term MP last week backflipped on the pledge and said she wanted to remain the ALP's candidate for the crucial western Sydney seat of Lindsay.
By that stage she had already been cast adrift by the New South Wales branch of the party, which had all-but chosen former state MP Diane Beamer as its preferred candidate.
The backbencher spoke with Mr Shorten last Thursday hoping for an intervention to save her candidacy, saying the Labor leader had always been a "champion" of hers.
But Mr Shorten repeated his view that recontesting the seat was not in the best interests of Ms Husar or the party.
The decision could see Ms Husar contest the seat as an independent.
"I love my job, so I would consider doing whatever I need to do to stay there and continue doing my job," she told Sky News on Tuesday.
Ms Beamer was the member for the electorate of Badgerys Creek and then Mulgoa between 1995 and 2011.
The seat covers much of the same geographic area as the electorate of Lindsay.
Mr Shorten and Ms Beamer have spoken in recent days, with the former state minister reportedly believing she has the Opposition Leader's blessing to contest the nomination.
Ms Husar has been contacted for comment.
