As Americans prepare to head to the polls on Wednesday, Australian time, Jim Chalmers said the implications of the result would flow on to countries around the world, including Australia.
"There are potentially big economic consequences of these midterms, particularly when it comes to any implications for the war in the Middle East," he told ABC Radio on Tuesday.
"Americans are dealing with a lot of the same issues that we are, whether it be inflation or these other pressures on people. The difference between us and the Americans is that they have a say when in when the war ends, and we don't.
"Australians are the cost-of-living casualties of decisions taken in DC and Tehran."
The midterms have all 435 seats in the House of Representatives up for grabs, along with one-third of the Senate.
The Democrats are tipped to end the Republican hold of both houses of Congress, according to opinion polls.
Criticism over President Donald Trump's actions in the war with Iran, which has led to a rising cost of living, has given Democrats the lead in traditionally Republican-leading states such as Texas, Iowa and Kansas.
If the Democrats control either chamber of Congress, it would limit Mr Trump's ability to pass legislation or block crucial appointments.
Democrats could also launch investigations into the Trump administration's actions.
Dr Chalmers said Australians would be watching the results closely.
"These midterm elections do seem like they have the whole world watching for good reason, and that's because the global environment is very volatile," he said.
"The war in the Middle East is a huge part of that volatility."
The war with Iran has led to fuel prices in Australia surging, with inflation also increasing above four per cent.
The rising inflation will likely lead to the Reserve Bank increasing interest rates for the fifth time in 2026, pushing the cash rate to an 18-year high.
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