West Australian Treasurer Ben Wyatt says he was disappointed after a meeting with federal counterpart Scott Morrison in which he failed to secure measures to prevent a shortfall of almost $2 billion in the state budget.
According to the latest ABS census figures, 60,000 fewer people are living in the state, which the WA Treasury estimates will lead to a $1.9 billion drop in GST share.
Mr Wyatt was seeking a one-year deferral in calculating the impact, but Mr Morrison said he legally could not intervene.
The federal treasurer said WA had endured several years with "a very unfair" GST allocation, but refused to go beyond "band aid" top-up payments for infrastructure projects.
Mr Morrison said he was focused on a long-term solution to GST distribution and would not move before receiving a Productivity Commission report next year.
"We're just going to keep working that issue," he told reporters in Perth.
"He (Mr Wyatt) needs to work on his Labor colleagues in the other states ... to convince them of his arguments, as do I need to work nationally on these same issues."
Mr Wyatt warned West Australians will turn on the Liberals at the next federal election.
"The treasurer, the prime minister can listen all they like, but Western Australians, I've got to say, have probably had a gutful of articulating the case and are now wanting to see some action," he said.
"I was hopeful to get at least some positive response around deferring the impact of the ABS data until it's finalised in June next year.
"The federal treasurer says he can't do that and I'm disappointed."
© AAP 2018