The US under a President Trump would withdraw Australia's security guarantee and become a "rogue superpower", according to a scholarly analysis commissioned by Australia's Lowy Institute.

The results would be so dire that the US election is the most consequential for world order since World War II, and the most consequential for the US since the election of Abraham Lincoln in 1860, the report says.

"For the first time one of the two major party nominees for the presidency, Donald Trump, is campaigning on a platform of weakening the core elements of the international order, including the US alliance system and an open global economy," concludes Thomas Wright from the Brookings Institution in Washington.

He says Australia's alliance with the US would suffer directly as a result.