According to local news outlet The Age, the state government is considering using a PPP model to procure and deliver the rail line, which aims to provide a major new route around Melbourne.
The government has previously discussed the use of value capture and other methods to help raise the investment needed for the multi-billion-dollar project.
However, the latest rumours have led opponents to call on the government to pause the project.
Shadow Minister for Major Projects, David Southwick, said: “This project is a mess and the Premier is clearly desperate to find ways to fund it.
“The Premier needs to explain how this project will be funded and what new taxes, levies or charges Victorians will pay as a consequence of her mismanagement.
“In the meantime, Jacinta Allan must do the responsible thing and delay signing any contracts.”