Australia's trade and military ties with the United States can withstand the return of Donald Trump to the White House, a former top diplomat says, praising "outstanding" US ambassador Kevin Rudd for building relationships across the political divide.

Dennis Richardson, who ran the Department of Foreign Affairs after serving nine years as US ambassador, told Q+A that Mr Rudd has what it takes to negotiate the bitterly fought race between Mr Trump and Democratic opponent Kamala Harris for the White House.

On the eve of the election, Prime Minister Anthony Albanese confirmed Mr Rudd would remain US ambassador, telling ABC Radio on Monday: "Australia decides who our ambassador is, and Mr Rudd is doing a terrific job."

"Rudd will be fine," Mr Richardson, who served as US ambassador under Bill Clinton and George W Bush, told Q+A on Monday night.

"He is extremely hardworking. He's been highly effective in Washington. He has good links across the political spectrum."

The federal opposition has questioned Mr Rudd's role, after Mr Trump called him "nasty" in an interview with politician-turned-broadcaster Nigel Farage in March.

"I hear he's not the brightest bulb, but I don't know much about him," Mr Trump said at the time.

 "If he's at all hostile, he will not be there long."

Mr Richardson called out "certain elements of the media" which he said "set out to sabotage" Mr Rudd.

"[Donald Trump] had a qualification to what he said. He said 'if he continues his negative approach when I'm president, he won't last long'. So, I think Kevin Rudd will be fine because he's doing an outstanding job," he said.

"I think that Anthony Albanese is too sensible to do anything but keep it on the right path."

Mr Richardson said AUKUS — the agreement with the US and UK to supply nuclear-powered submarines to Australia — would proceed.

And he said Mr Trump would stick by bilateral trade agreements, despite threatening 10 per cent tariff hikes on imported goods.

"I don't believe either will be under threat with a Trump presidency," Mr Richardson said.

"It will be an interesting ride. There will be surprises.

"There will be points in time when people will question whether those agreements will come under pressure, but I personally believe that they're not under threat at all."

Scaramucci: Trump 'useful idiot' to Russia

There was more concern about what Mr Trump's isolationist rhetoric would mean for Russia's war against Ukraine.

Anthony Scaramucci, a former adviser to Mr Trump before turning against him, told Q+A the former president is "a useful idiot" for Russian President Vladimir Putin.

"We have got to get Trump out of there and reset this thing," he said, worried about Mr Trump and Republicans in Congress ceasing financial and military aid to Ukraine.

"Whether the United States likes it or not, it is the biggest economy with the biggest military and we have to be engaged with our allies to ensure this freedom. Because any one domino that gets toppled could lead to your domino."

Mr Richardson agreed Mr Putin "would clearly like Trump to win" and that Mr Trump may "put pressure on Ukraine to come to some sort of agreement with Russia".

"I think NATO partners and Ukraine would be very nervous about a Trump victory," he said.

Liza Martin, a Ukrainian now living in Australia, told Q+A her country was glued to the US election.

"This is our number one thought right now because there is so much at stake," she said.

"Our freedom is at stake. Our country's existence is at stake. It is a very important thing for us, this election."

Trump 'more aggressive, violent'

Anthony Scaramucci has been campaigning for Ms Harris and believes she will win.

"I feel she will win based on momentum. It is not vibe, it is just based on momentum," he said, calling Democrats "way more organised than [Donald Trump]".

He took more shots at Mr Trump, who fired him after 11 days as White House communications director, calling him "way more aggressive" and "way more violent" than his first White House term.

"Donald Trump is running on four pillars. He's running on cruelty, he's running on anti-immigration, he's running on racism and he's running on misogyny. If you don't believe me, just listen to the speeches and listen to what he's saying," he said.

"Trump is a third-party insurgent that's running off something that's been in the country forever, it is called American nativism … It was a slogan in Nazi Germany. Hitler said many times that Germany is for Germany and only for Germans.

"We have this element in our midst. We've been able to suppress it, we've been able to put it down, but in this case, Trump is attracting these people.

"It is a shame to watch."

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