A major factional row has erupted in the NSW Labor Party over preselection for a byelection in the “heartland” seat of Wollongong.

The vacancy was created by the shock resignation of Noreen Hay, who occupied the constituency for 12 years.

As things stand, there are two certain nominations for preselection: Wollongong University academic Paul Scully, from the left, and Deb Langton, a moderate, local solicitor and former wife of disgraced ex-Kiama MP Matt Brown.

A third candidate may be John Rumble, the son of former Illawarra MP Terry Rumble.

A fourth option has also been raised: NSW Labor’s head office may parachute its own candidate into the seat to avoid bad publicity from a preselection mud wrestle.

Langton, who combines her legal career with the management of three restaurants, has criticised reports of an outsider being given the plum ALP seat.

“It would be very disappointing if that were the case,” she said. “The ALP would be letting themselves down. Rank and file [selection] is a democratic process and should be used in all circumstances.”

The byelection, which is due to be held in November, will be a test for Opposition Leader Luke Foley and Kaila Murnain, the party’s new general secretary, who succeeded the disgraced Jamie Clements earlier this year.

Clements supported Hay when she controversially won preselection over Scully to contest last year’s state election, and there would be mutiny in the Illawarra’s dwindling branches if another “stitch-up” were to unfold.

Hay was cleared of any wrongdoing after a long-running police inquiry into local ALP branches, and she escaped criticism when the anti-corruption watchdog, the Independent Commission Against Corruption, conducted a sensational inquiry into Wollongong City Council, which resulted in its sacking.

Last month Hay decided to terminate her political career.

In her valedictory speech on August 4, she spoke of her pride in becoming the first female MP for Wollongong, the first female whip in Parliament and the first female chair of the Public Accounts Committee.

[Tough questions for NSW Labor, with Wollongong byelection more likely]

There was some head-shaking when she told MPs: “During my time as the member for Wollongong it has been essential for me to keep the faith and trust of my community.”

She offered no clue as to why, after entering Parliament in 2003 as an outspoken left winger, she abruptly joined the right-wing Centre Unity faction, eventually becoming its convener.

The London-born MP, a former regional secretary of the left-wing Miscellaneous Workers Union  and Chelsea supporter, told Parliament that former Labor treasurer Eric Roozendaal was “an absolute pushover” when it came to finding $30 million to build the Western Grandstand at WIN Stadium in Wollongong.

She condemned the media coverage that “I have been subjected to over the past 13 years”, adding that election candidates should be “encouraged and supported, particularly against character assassination and criticisms based on their looks and age”.

“After all, many members of Parliament would not be in Parliament today if the same criteria were applied to them.

“I leave with my honour, my integrity and, most importantly, my self-respect intact.”

Many MPs rose in their seats to clap when she had finished. It was difficult to know whether it was in appreciation or with relief.

Her predecessor in the Wollongong seat, Col Markham, has written to Labor’s head office demanding an investigation into the 2014 preselection process, in which he alleges there were “doctored minutes and dodgy attendance books”.

He is seeking “a full and thorough review of all records of branches in the Illawarra” to restore party integrity before November’s byelection.

Noreen Hay’s public career may not be over quite yet.