Bill Shorten has thrown his support behind Queensland's flagship infrastructure project, promising to partially bankroll Labor's Cross River Rail should he win the next federal poll.
The state government had committed to funding the $5.4 billion line alone after failing to secure money from the Turnbull government.
Some of that money will now go towards other projects, state Treasurer Jackie Trad told reporters on Monday.
"Bill Shorten's offer of $2.24 billion is a game changer for us," she declared.
Mr Shorten said an initial $800 million instalment would be paid over three years, starting 2022.
The remaining funding would be split 50-50 spilt with the state government over 30 years to repay a yet-to-be finalised agreement to build the above ground section of the line.
The Cross River Rail, a 10km of line between Dutton Park and Bowen Hills and four new underground stations at Boggo Road, Woolloongabba, Albert Street and Roma Street, is expected to be complete by 2024.