A Victorian Labor MP will either resign or be booted from the party after siding with a disgraced colleague over the government's 2014 election rorts scandal.
Kaushaliya Vaghela crossed the floor in Victoria's upper house on Wednesday to ensure former Victorian Labor powerbroker Adem Somyurek's motion passed 19 to 17.
It calls on Victorian Ombudsman Deborah Glass to reinvestigate the 2014 "red shirts" scandal in which $388,000 of taxpayer money was misused to pay political campaign staff and specifically any role Premier Daniel Andrews may have played in it.
Mr Andrews said the rules were clear that all Labor caucus members must vote with the party or face expulsion.
"Let's wait and see whether that's necessary," the premier told reporters on Thursday.
Mr Andrews said he didn't watch the vote and could not recall the last time he spoke with Ms Vaghela, a member of Labor's factional right who was dropped from the party's ballot last year for the November election.
"I wasn't entirely surprised," he said of his reaction to her vote.
Mr Somyurek said he told Ms Vaghela her decision to cross the floor was "courageous" and branded Mr Andrews a "coward", calling for him to "take responsibility" for the red shirts scheme while also conceding he could go to jail for his role.
"If I go to jail so does 24 other Labor MPs," Mr Somyurek said.
The premier refused to comment on the accusation he "designed" the scheme, on the grounds the matter has been referred to the Ombudsman.
Mr Somyurek's motion requests Ms Glass also looks at Mr Andrews' social media staff, Labor-linked appointments in the public service, and the role of lobbyists in party politics
It also invited Ms Glass to consider her powers to share information with the Independent Broad-based Anti-corruption Commission, with the view to expanding the scope of its ongoing joint investigation with her into Labor branch stacking.
Mr Somyurek remains at the centre of that investigation as a key player in the branch-stacking scheme, a practice that is not illegal but against Labor rules and involves the systematic payment of memberships to influence election candidate preselection.
When questioned by IBAC last year, Ms Vaghela said she believed her husband Dinesh Chauhan mainly did factional work in the offices of MPs Robin Scott, Marlene Kairouz and Mr Somyurek.
IBAC heard from federal Labor MP Anthony Byrne, a former close ally of Mr Somyurek, that Mr Somyurek threatened to "take people out" of preselections and reward others for their stacking efforts, including Ms Vaghela.
In a statement on Wednesday night, Ms Vaghela said she knew all about branch stacking as a former factional staffer and it needed to be investigated in both right and left factions.
The "red shirts" rort involved more than 20 past and present Labor MPs breaching parliamentary guidelines by diverting staff to help campaign for members.
In 2018 Labor paid back the money used in the scheme following an investigation by Ms Glass, but no criminal charges were laid following a separate probe by Victoria Police.
In a statement, an Ombudsman spokesperson said Ms Glass would report to parliament "in due course" on how any investigation would be conducted should a referral be made.
An IBAC spokesperson said every complaint it received was assessed to determine whether the watchdog would investigate it, refer it to another organisation, or dismiss it.