Former US Ambassador and Labor leader Kim Beazley has warned that "immense responsibilities" will fall on Australia's shoulders to steer Donald Trump towards a more responsible foreign policy should the erratic billionaire become US president.

Mr Beazley said that as the US ally that provides the most to the superpower and demands the least, Australia might have the ear of Mr Trump, who has outlined a deeply isolationist approach that would cut allies loose if they don't pay their way.

He said this meant Canberra would need to push hard for a Trump administration to take a course that continued constructive US leadership rather than withdrawing, as the Republican candidate has threatened.

"A Trump presidency won't be a question of 'hold on to your hats for four years' and then sanity will rule," Mr Beazley wrote in a commentary posted on the Australian Strategic Policy Institute's website.