CANBERRA, March 25, 2025 (BSS/AFP) - Australia will fortify its economy against damaging US tariffs in a government budget to be unveiled Tuesday, Treasurer Jim Chalmers said as he touted plans to boost homegrown "green" manufacturing.

The annual budget sets the scene for the left-leaning government to call a general election, an announcement widely expected by the end of the week.

After booking two years of budget surpluses, Australia is almost certain to return to deficit as it sets aside cash for cost-of-living relief and other election pledges.

Chalmers said this year's budget would prepare the country for "global economic uncertainty" fuelled by US President Donald Trump's on-again, off-again tariffs.

"We're a very trade exposed country. We're not uniquely impacted by these tariffs out of Washington DC but we've got a lot of skin in the game," he told national broadcaster ABC.

Chalmers pointed to the global appetite for so-called "green metals", an emerging market that Australia is eager to corner.

Metals such as steel and aluminium are typically produced in hulking factories that rely on polluting coal-fired power.

Australia and others instead seek to power these factories with renewable electricity, lowering emissions in the process.

"Our best defence against global economic uncertainty is a more resilient economy," he told reporters.

"And that's what the billions of dollars, for example, that we're investing in green metals is all about."

Australia will use the budget to bring forward around US$600 million in defence spending, Defence Minister Richard Marles said on Monday.

Washington has been piling pressure on close allies such as Canberra to pour more money into training, weapons and other military hardware.

Australia is already in the middle of an ambitious program to re-tool its creaking defence force, stocking up on long-range strike weapons as China flexes its naval might in the region.

Australia is due to hold a general election by May 17 at the latest.

Recent polls show the Labor government locked neck-and-neck with its conservative Liberal party rivals.