Independent Senator Nick Xenophon has questioned the federal government's decision to allow more US troops to be stationed in the Northern Territory.
A visit by US President Barack Obama has been used to announce a plan to have 2500 Marines based in Darwin by 2016.
The expansion of the existing collaboration between the Australian Defence Force and the US Marine Corps and US Air Force will allow the US to enhance its presence in the Asia-Pacific region.
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Senator Xenophon on Thursday questioned the future outcome of the decision.
"Most Australians would feel comfortable with US troops under an Obama administration, but maybe not a Tea Party administration," Senator Xenophon told AAP on Thursday.
The Tea Party is a US right wing political movement.
Senator Xenophon's concerns mirror those of the Australian Greens.
Greens leader Bob Brown fears nuclear submarines could be stationed off the coast of Australia as part of a wider US military build-up in the Top End.
