Ms Plibersek said Mr Trump's latest comments, in which he suggested the November 8 election was being "rigged" by a corrupt media, should free MPs from the usual convention of not commenting on the domestic politics of other countries.

"He's broken so many conventions I think it's fair enough for us as Australians to say we are deeply concerned about the security concerns his candidacy raises," Ms Plibersek told Sky News on Sunday morning.

Ms Plibersek, who was Labor's foreign affairs spokeswoman until the July 2 election, said Mr Trump's "cosying up to Russia" as well as his inability to act "as a unifying force for the United States" made him an unacceptable candidate.

"It shows he's unsuitable to lead a country like the US that plays such an important role in the world," Ms Plibersek said.

Labor leader Bill Shorten attracted the criticism of the Turnbull government during the election campaign when he said Mr Trump was "barking mad".

But Mr Trump's comments about women a week ago forced even Prime Minister Malcolm Turnbull to say he found them "loathsome".

Government ministers who made comments about Mr Trump last week limited their interjections to his remarks about women.

Ms Plibersek's colleague, Penny Wong, who took over the foreign affairs portfolio from Ms Plibersek after the July 2 election, was more measured saying she did not like "hypothetical" questions but noted the "unusual situation" Mr Trump presented as a possible US leader.

"There are many things Donald Trump says which I don't agree with, which we don't agree with," Senator Wong told ABC television.

"[But] the US alliance has continued to survive and strengthen through decades."

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