Speaking at an address at the National Press Club on Thursday, Mr Palmer said his party would preference the major parties and the Greens last in the Senate, while preferences in the lower house were yet to be determined.

However, Mr Palmer said the party would be likely to preference lower house candidates who had backed the party's stance against vaccine mandates on an individual basis.

"I'd put the Greens ahead of Liberal and Labor. That's my personal perspective, because they haven't been in government and they haven't been responsible for this debt," Mr Palmer said.

In a speech to outline the United Australia Party's economic policy ahead of the election, Mr Palmer said reducing the government's rising debt levels would be a key priority.

He also proposed setting a maximum cap on interest rates for housing loans of less than three per cent for the next five years, while also calling for a 15 per cent export licence for iron ore exports.

Mr Palmer spent millions in advertising at the 2019 election and failed to win a single seat.

With the federal election just days away from being called, Mr Palmer said he would spend more than $70 million on the 2022 campaign.

Of that, $31 million has already been sunk into election ads, with a further $40 million expected to be spent in coming weeks in the lead-up to the May poll.

"We don't get coverage by news generally, so if you balance the number of articles against the number of ads, you'd find that our ideas are less prominent than the traditional parties," he said.

"But we do believe in democracy, and democracy means a diversity of ideas."

The unvaccinated billionaire also revealed he had taken a cocktail of drugs following his recent bout of COVID-19, which saw him hospitalised earlier this year.

The infection forced Mr Palmer to postpone his press club address.

The former federal MP also had pneumonia at the time of his infection, however, he did not know what drugs he had taken as part of the cocktail.

He remains confident of winning seats at the election, but doesn't consider it as a measure of success.

"We've got a much stronger team this time and there's more need for our message this time," he said.

Mr Palmer is running for a Senate seat while the party's sole parliamentary representative Craig Kelly - a former Liberal MP - is seeking to retain his Sydney seat of Hughes.

Australian Associated Press