A rail link to Melbourne Airport could end up being built regardless of who wins the next state election, with both major parties declaring they are open to the idea as part of a broader plan to meet the city's long-term needs.

With new research revealing a train line from the CBD to Tullamarine could generate benefits of up to $1.40 for every $1 spent, the government and the opposition have not ruled out taking the policy to the Victorian poll in 2018.

Both major parties are interested in adding a rail link to Melbourne Airport.

In a notable strengthening of language this week, Premier Daniel Andrews said the proposal had merit, but it was important to get the government's other transport priorities – including level crossing removals and the Metro Rail Tunnel – ticked off first.

"There'll be a time when an airport rail link stacks up. It's not an unworthy project … but it's about the sequence in which you build these things," he said.