Rail travel between Geelong and Melbourne will be twice as quick once a new fast-rail link is built, but Victoria is criticising Canberra for jumping the gun on funding.
The $2 billion fast rail commitment will be in the budget as one of at least six fast-rail projects around the nation linking regional centres with large cities.
Prime Minister Scott Morrison conceded the Geelong to Melbourne link won't be ready for years to come, with construction expected to start within two years.
"To take the pressure off our fast growing cities you need to be able to improve your links with your satellite cities around the country," Mr Morrison told reporters in Geelong on Friday.
The funding for the 20-year fast-rail plan will be included in the April 2 budget, but the project relies on Victoria matching the $2 billion commitment.
As part of the plan the federal government is putting $40 million towards developing five new business cases across the country for the fast-rail links, which will travel at an average speed of 160km/h.
Such a speed will see the 80km Melbourne to Geelong commute cut in half to 32 minutes.
But Victorian Transport Infrastructure Minister Jacinta Allan said Mr Morrison had jumped the gun on the project, while Victoria is spending $50 million on finding out how to make it work.
"It's been interesting today to see an election eve thought bubble come from the prime minister," she told reporters.
"Two billion dollars is simply not enough money to do that work."
Mr Morrison said the money was a start, and based on advice from experts about what it would cost to upgrade the line.
"That's what business cases are for, that's our understanding at the moment, if the costs are greater than that then we'll have to address that at the time," he said.
Opposition Leader Bill Shorten said the announcement was a cynical attempt to chase votes in Victoria.
"How do you know when there's going to be a federal election? The Liberal Party discover infrastructure in Victoria. What a coincidence," Mr Shorten told reporters in Melbourne.
The fast-rail announcement is the latest slice of the government's population growth plan, with Mr Morrison announcing earlier this week the number of annually available immigration places will be cut from 190,000 to 160,000.
OTHER RAIL LINKS IN THE WORKS
* Brisbane to the Gold Coast
* Melbourne to Albury-Wodonga
* Melbourne to Traralgon
* Sydney to Wollongong
* Sydney to Parkes.
Australian Associated Press