NSW Premier Chris Minns has left the door open to shutting down a $25 billion metro rail project that would put Parramatta within 20 minutes of the Sydney CBD.
Sydney Metro West was initially set to cost about $13 billion and open around 2028 but cost blowouts and delays under the former coalition government have renewed fears Labor will ditch the project.
The premier is urging the public to allow an eight-month independent review to run its course.
An interim report is due ahead of the September 19 budget, before a final report in December.
"If we make a decision to axe the project ... you could take my head off then," Mr Minns told reporters on Wednesday.
"But in the meantime, let this review do its job and report back to government."
As well as providing a faster connection to Sydney's second largest CBD, Metro West would open more of the city's inner west to rail and enable the high-density housing essential for the city to address supply challenges.
But the $13 billion in cost overruns for the project, coupled with $9 billion extra expected on Sydney Metro City and Southwest's original price tag, warranted an investigation, Mr Minns said.
"The bottom line is, we have to work out a way to pay for Metro West that doesn't destroy the budget because that's what we've been left with by the previous government," he said.
Opposition Leader Mark Speakman was more sceptical about the suggestion Labor was caught unaware by the cost blowouts.
Mr Minns went to the election promising to complete both metro projects and delaying or cancelling them would have flow-on effects for housing, he said.
"We've got an urgent need for housing now in Sydney," Mr Speakman said.
"Any delay delays that housing."
He supported the state government seeking funding for the projects from the federal government or through developer contributions if that meant keeping the Metro project on track.
