George Brandis warns not to erode Kevin Rudd's standing in ...

The federal opposition's rush to jump on US presidential hopeful Donald Trump's character assessment of Australia's envoy in Washington could erode his standing in the capital, a former senior diplomat has warned.

During an interview with British politician-turned-broadcaster Nigel Farage, Mr Trump said he had heard Dr Rudd "was a little bit nasty" and "not the brightest bulb".

The comments were prompted by Dr Rudd's own turn of phrase, prior to becoming ambassador to the US, when he described Mr Trump as a "destructive president" and a "traitor to the West".

George Brandis served as Australia's high commissioner to the United Kingdom from 2018 to 2022, after almost two decades as a Liberal senator for Queensland where he became one of the most senior politicians in the party.

"I think it's very important that Australia's senior diplomatic representatives, whether they be career diplomats or political appointees, should have bipartisan support," Mr Brandis told ABC Radio National.

"If they don't, it diminishes their authority, and therefore diminishes their influence in the country to which they are accredited, and that's plainly not in Australia's national interest."

Mr Brandis said there was a risk Mr Trump's comments were being "over interpreted".

"I watched the interview last night, he barely seemed to know who Kevin Rudd was when asked the question," Mr Brandis said.

"And his response that's created such a flurry in the media today was a highly conditional response — he said if he's hostile, he won't last for very long.

"Donald Trump is infamous for making rather wild and off-the-cuff claims that don't in the end amount to very much, so it's obviously something that the government should keep an eye on, but I wouldn't over interpret it."

The former high commissioner, now a professor at the Australian National University, suggested the interviewer had achieved his goal.

"I know Nigel Farage, he's a charming charlatan, who's building a reputation as a broadcaster in the United States," Mr Brandis quipped.

"So obviously, he is interested in attracting as much importance to his interviews as possible."

Earlier, shadow cabinet minister Barnaby Joyce described Kevin Rudd as "cooked".

"He can't possibly be the ambassador if president Trump becomes president Trump Mark Two," Mr Joyce told Channel Nine.

"You might as well drag him back and send him to another country, send him over to France or The Hague, or make him deputy secretary of the United Nations.

"Do something else with him – there's lots of other jobs, lots of wonderful Pacific islands, they need Kevin."

Health Minister Mark Butler, who served as a cabinet minister during Dr Rudd's second prime ministership, defended him.

"He's bringing his usual work ethic to networking in America, as he did so notoriously here in Australia.

"He's widely sought out for his advice, particularly around China and Xi Jinping.

"We're very confident that whatever happens in November, he'll be able to work with all US administrations."

Prime Minister Anthony Albanese lashed out at critics of Dr Rudd, as the federal Opposition Leader Peter Dutton urged him to take Mr Trump's critique seriously.