Jaclyn Symes has been named government whip in Victoria's upper house after embattled MP Cesar Melham resigned.
She defeated Philip Dalidakis in a caucus vote on Tuesday.
Mr Melham resigned on Monday night citing speculation about his role in the Labor state government, following allegations at the unions royal commission that he did a deal when he was a union official that dudded workers out of penalty rates.
Ms Symes was an adviser to former Labor MP Rob Hulls before winning a Northern Victorian Region seat at the 2014 election.
She declined to speak to the media after the vote, while Mr Melhem also made no comment.
Ms Symes won't have to keep her upper house colleagues in line until Wednesday, with condolence motions for former premier Joan Kirner likely to dominate Tuesday's sitting, and question time cancelled.