Breathe a sigh of relief, Australia - had Mitt Romney won the day, it would have made for an ugly time with our big alliance partner.

Barack Obama, by contrast, will now be judged in his second term on a pledge to ''pivot'' America's attention to this neighbourhood. That will bring its own challenges for Canberra, especially as the US military eyes off extra Australian staging posts.

But Obama's attitudes to the world - and his view of Australia - have become clear over the past four years, giving a predictable basis to engage the US in Asia.

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Putting Romney in the Oval Office would have introduced another unknown quality into an already volatile region.By volatile, read China. Romney looked set to spark a currency war with Beijing out of a misplaced diagnosis of America's economic woes — blaming China for the US addiction to debt — and the cost could have plunged the economies of Australia's two major trading partners into crisis.

How well America and China get along, as the Gillard government's Asian Century white paper acknowledges, is crucial to the temperature in the region and to Australia's prosperity.

Obama will still make demands of allies. His administration will put more pressure on Australia over military spending for example.

Labor's cuts to Defence have rankled Washington, coming despite the Gillard government's regular boast that Australia sailed through the global economic crisis, has low unemployment and an economy ''the envy of the world''. Americans are increasingly free with once private complaints that Australia is freeloading on the expensive US security commitments to the region.

But this criticism would have been even sharper under a Republican president. Romney, himself, was something of a novice in foreign policy, but the hawks advising him and the Tea Party surrogates on the margins would have been very hard to satisfy.

Especially for Wayne Swan, who had already branded them ''cranks and crazies''.

A Romney presidency would have also heralded a more bellicose US policy towards the Middle East, dragging US attention away from Asia but also making demands on Australia over problems a long way from home.

There are personnel questions to settle. With Hillary Clinton expected to step aside, and with her some of the key officials in the State Department responsible for Asia also likely to go, Australia will need to get to know the next crop of officials responsible for carrying through the promised pivot.

And the Americans are doubtless getting ready for the prospect of change Down Under - maybe President Obama will welcome a Prime Minister Tony Abbott to the White House sometime this term.

Daniel Flitton is smh.com.au senior correspondent.