Relatively-unknown Sydney MP Chris Minns believes he can be the "new generation" leader Labor needs in NSW after three successive election losses.
But the member for Kogarah's bid could be derailed by some in the union movement and party head office.
Mr Minns was the first to formally announce he will be nominating for the NSW Labor leadership on Thursday, two months after the party's resounding loss to the coalition in the state election.
The father of three - from the party's right faction - admits Labor needs to change and believes it can regain the trust of voters by turning to a new leader.
His chances, however, could be hurt by his fractious relationship with NSW Labor's general secretary Kaila Murnain - believed to stem from Mr Minns' friendship with the previous state secretary Jamie Clements.
But Mr Minns said it was time to "put the past in the past", adding the ballot system meant she could not "block me".
His bid could also be thwarted by some unions, who were left upset by critical comments he made during his inaugural speech to parliament.
Within minutes of his announcement, the Australian Manufacturing Workers Union said it didn't have confidence in Mr Minns' ability to unite the labour movement.
"His views on the role of unions in the Labor party, as well as his views on critical policy areas ... are unacceptable for someone in the role of opposition leader or premier," AMWU NSW and ACT secretary Steve Murphy said.
And one branch of the meat industry union said he was "unfit to be a leader."
"We will not, under any circumstances, accept Mr Minns as NSW Labor Party leader," the AMIEU's Newcastle and Northern branch said in a statement.
Mr Minns is hopeful he can convince them, despite calling for a reduction of union control over the party.
"I ask them to suspend their judgment," he said.
He unsuccessfully ran against ex-leader Michael Daley following a spill in November 2018 but is confident his fresh approach makes him the best candidate.
"NSW Labor hasn't been successful since 2010. What we are doing isn't working," he told reporters.
"We have to provide answers to the pressing problems facing NSW ... I'm the best person to carry out those goals."
Mr Minns flagged public transport, climate change, revitalising Sydney and keeping a balanced economy as his key issues.
Nominations for the Labor leadership close on Friday afternoon.
Frontbenchers Jodi McKay (Strathfield) and Kate Washington (Port Stephens) are also believed to be considering a tilt.
Mr Minns expects Ms McKay to nominate and welcomed the contest.
If two or more candidates emerge, a ballot will be held for rank-and-file members and the parliamentary party.
The process will take a number of weeks.
Upper house MP Penny Sharpe has been interim leader since Mr Daley stood down from the top job following the March 23 poll.
NSW Labor held off selecting a new leader until after the federal election to prevent a distraction to Bill Shorten's national campaign.
Australian Associated Press