Labor has officially picked former New South Wales state politician Diane Beamer as its candidate in the marginal western Sydney electorate of Lindsay, after sitting MP Emma Husar was formally disendorsed last week.

Key points: Ms Husar vowed to fight for her position after being disendorsed

Ms Husar vowed to fight for her position after being disendorsed There has been significant speculation about Ms Husar's future after she said "slut-shaming" had ended her career

There has been significant speculation about Ms Husar's future after she said "slut-shaming" had ended her career Among the possible options for Ms Husar are to challenge the disendorsement decision or to run as an independent candidate at the next election

A meeting in Sydney today locked in the decision, foreshadowed in late November, after Ms Husar said she would not contest the next election.

The embattled MP maintains she was forced to announce her resignation in August after allegations of harassment and misconduct were levelled against her by former staff.

Ms Husar vowed to fight for her position, and is understood to be considering her options in the wake of today's decision.

The ABC understands Ms Husar did not nominate for today's preselection ballot.

In a statement, Ms Husar said she remained disappointed by her disendorsement and that the reasons behind it had not been explained to her.

"The rationale should be provided under party rules. I wasn't asked or given any opportunity to make any representations. This was all done behind closed doors," she said.

"The moves since Friday have been swift and decisive, and have effectively left me a Labor outsider.

"This brings me deep sadness, as this is a party capable of great things. It's clear now that for whatever reason, I'm not to be a part of it post May."

Diane Beamer is the new Labor candidate for Lindsay. ( Twitter: NSW Labor )

There has been significant speculation about Ms Husar's future after she said "slut-shaming" had ended her career.

An investigation by the NSW Labor Party found Ms Husar subjected staff to unreasonable management, but did not uphold claims of sexual harassment and lewd conduct and argued there was no resign for her to resign.

Among the possible options for Ms Husar are to challenge the disendorsement decision or to run as an independent candidate at the next election.

On Thursday, the backbencher announced she had launched a defamation suit against Buzzfeed for its reporting on the allegations against her.

Opposition Leader Bill Shorten reiterated on Friday that Ms Husar's original resignation had been accepted by the party, and it was still in Labor's and her best interests not to contest the seat.

Ms Beamer was a state minister and the member for the electorates of Badgerys Creek and Mulgoa between 1995 and 2011 — electorates covering much of the same geographic area as the federal seat of Lindsay.