South Australian and Tasmania are so-called "beggar" states which should exit Australia's federation in a "Begxit", a crossbench senator has argued.
Liberal Democrats' David Leyonhjelm took aim at governments he says are not pulling their weight on GST as he debated changes to the tax's distribution on Monday night.
Legislation to put a GST floor of 75 cents and boost the pool with federal money is set to pass the Senate on Tuesday with support from the major parties.
But Senator Leyonhjelm said the coalition and Labor were "infested" with disproportionate numbers of beggar politicians from those states.
"What we need is a Begxit - where the beggar states exit the federation," he told parliament.
"But the beggar governments of these states never do anything for themselves so they won't exit of their own accord. The rest of us with the Liberal Democrats, at the vanguard, will need to arrange it for them."
He said SA and Tasmania were the having of the bulk of $9 billion in federal money thrown at them under the plan.
"These beggar governments continue to hold back the prosperity of the people they are supposed to represent."
The government says the change will deliver extra untied funding to the states and territories over 10 years and from 2026-27 an additional $1 billion each year in perpetuity.
Labor backed the laws when the government announced a guarantee every state and territory will be better off.
Australian Associated Press