Questions are being asked about the future of US-Australia relations after former Republican president and second time presidential hopeful Donald Trump called the government's US ambassador Kevin Rudd "a little bit nasty" and warned he would "not be there for long".

The former prime minister called Mr Trump "the most destructive president in history" before he was appointed as Australia's man in Washington.

As opinion polls point to the possibility of a second Trump presidency and an end to President Joe Biden's term in November, critics say Dr Rudd's ambassadorship could endanger the alliance and key deals between the US and Australia.

But Deputy Prime Minister Richard Marles says the government and Dr Rudd will be able to work across the American political spectrum.

"We have a sense of confidence that no matter what the result is in November, the relationship between our two countries will be strong," he told ABC Insiders on Sunday.

"We work very closely with the Biden administration, as we will work closely with the incumbent administration in America in any moment in time, and that's where our efforts are at."

The Australian government worked with the Trump administration under the ambassadorship of Arthur Sinodinos and former treasurer Joe Hockey, but Dr Rudd has not operated under the same leadership.

There are also fears a second Trump presidency could lead the US to renege on the trilateral security alliance between America, the UK and Australia - also known as AUKUS.

But Mr Marles says there is "no reason" to believe a Trump administration would be anything but supportive of the deal.

"You need the support of the entire political spectrum in America to get things done, and that's what we've done in terms of AUKUS," he said.

In December, the US Congress passed legislation that enabled substantial provisions to the AUKUS nuclear-powered submarine program.

The government has attributed the success of the deal to Dr Rudd's dealings across the Democrat-Republican divide.

"We have a sense of confidence about the support across the spectrum because it makes strategic sense for the United states," Mr Marles said.

Australian Associated Press