The Pauline Hanson-led party has been placed under renewed scrutiny as opinion polls show it easily leading the coalition and challenging frontrunners Labor in some surveys.
Senator Hanson has recently walked back a number of policies, including lifting defence spending to five per cent of economic output - a measure that could cost hundreds of billions of dollars.
One Nation treasury spokesman Barnaby Joyce could not commit to putting all of his party's policies through the parliamentary budget office for independent costing.
"We're going to give our very best attempts to," he told Sky News on Sunday.
"You've got to realise and I think it's fair to accept that we don't have the resources.
"We have ... a real trap where they say we want you to act like a major party, but we're not going to give you the resources."
While Labor has positioned One Nation as the party of grievance, the coalition has sought to attack its economic policies.
In a recent speech, Opposition Leader Angus Taylor sharpened his attack on the rival right-wing party, saying just four of One Nation's commitments could cost the federal budget $1 trillion over a decade.
"They have no clear or credible plan for how they'd pay for these commitments," he said on Thursday.
But Mr Joyce questioned the trillion-dollar figure while offering few specific details of where his party would cut spending, citing the need to reduce duplication between tiers of government as an example.
"We only have four people and I'm doing a lot of work on my own," he said.
"I'm back to accountancy and being an economist at the moment.
"I need further resources to get to the bottom of this."
Amid anger among voters about high house prices and cost-of-living pressures, Mr Joyce said One Nation would look to give the Reserve Bank a major shake-up.
He said the central bank should be "more independent" and able to make public statements about government spending.
"I do have some sympathies for the Reserve Bank because they're given a hammer, and it's a hammer that there's so many issues," he said.
Asked about Senator Hanson's call for Australia to become a "monoculture", Mr Joyce doubled down on his party's rejection of multiculturalism.
"I believe in an Australian culture ... and whether you're Vietnamese heritage or Chinese heritage or African heritage, it's not the issue," he said.
"If you reside in Australia, there has to be stringent guardrails, because the liberties and the freedoms of other people are determined by your interaction with them."
Liberal frontbencher Dan Tehan said the coalition supported multiculturalism "but with Australian values" after Mr Taylor previously refused to say whether he backed the approach.
"(The) problem we have is with the Labor Party in that they're not pursuing those Australian values within multiculturalism and that's what we want to see as a coalition," he told Sky News on Sunday.
Education Minister Jason Clare said Australia was a multicultural country "whether you like it or not".
"The sad part about this is the Liberal Party's got a pretty proud history here, (they) are responsible for getting rid of the White Australia policy," he told Sky News.
"Now they're so spooked by One Nation that they can't even say the word multiculturalism."
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