Treasurer Michael O'Brien revealed on Tuesday that the East West Connect consortium headed by construction giant Lend Lease had been chosen as the preferred bidder to deliver the first stage of the toll road.

The state government has begun negotiations to finalise the $6billion to $8billion contract with the consortium, which also includes French construction company Bouygues, Spain's Acciona Infrastructure and Lend Lease's financing arm Capella Capital.

Mr O'Brien said the group had significant experience in delivering projects of a similar size.

"Following an extensive evaluation process, the Victorian government will now enter into exclusive negotiations with East West Connect to deliver what is one of the world's largest infrastructure projects currently out to tender."

Mr O'Brien said he was limited by what he could say because the tender process was still "live".

"There are not only contractual issues to be resolved with the bidder but also planning decisions that the Planning Minister still has to make before all these matters can be finalised."

He said he was "very pleased" with the design put forward by the consortium, and its proposal for the project was within budget.

"We do expect this project to go ahead, to be delivered on time, to be delivered on budget." More details would be released once it was "commercially safe", he said. He said the project's assessment committee unanimously recommended the East West Connect consortium because it provided "the best overall package for Victorians".

The government expects it will begin building the eastern section of the toll road this year.

Voters are yet to be convinced about the merits of the road, which links the Eastern Freeway to the Tullamarine. Polls have consistently ranked the project behind other transport priorities including a new rail tunnel in the city and level-crossing upgrades.

Mr O'Brien defended the government's decision to sign the contract just weeks before the November state election.

"We were elected to fix the problems and build for the future. Building the East West Link is about building for Victoria's future."

Opposition Leader Daniel Andrews said Victorians should be able to decide on whether the project went ahead. "Fancy a situation where the Premier is actually afraid of his own pet project ... he won't take this to the election."