The much-anticipated extension to the $11 billion Metro Tunnel has been overlooked by both the Coalition and Labor in their slew of multibillion-dollar transport promises.

Victoria's peak motoring body is calling on the major parties to consider funding plans for a second underground rail tunnel, Melbourne Metro 2, just days ahead of the federal election.

The RACV says the rail tunnel linking Clifton Hill and Newport via Fishermans Bend is a "top priority" project, but has been completely overlooked.

Melbourne Metro 2 would link Clifton Hill and Newport via Fishermans Bend. Credit:Mal Fairclough

The Coalition and Labor have promised to fund fast rail from Melbourne to Geelong and the suburban rail loop respectively, while both have committed $5 billion for the airport rail. But neither has put money towards Metro 2.