An influential senator believes it's inevitable Australia would reconsider its alliance with the United States if Donald Trump wins November's presidential election.
As Opposition Leader Bill Shorten declared the Republican candidate "entirely unsuitable" to be president, Nick Xenophon said Australia shouldn't be just going along with the US.
"I don't think we should hitch our wagon to a country run by someone like Donald Trump," the independent senator told reporters at Parliament House on Tuesday.
Mr Shorten told the Committee for Economic Development of Australia conference he wasn't the only one relieved that Mr Trump's prospect of becoming president was fading with every passing day and every demeaning and disgusting comment.
"By his own words and his own actions, he has confirmed the worst fears of millions in the United States and beyond its borders - he is entirely unsuitable to be leader of the free world," he said.
But Liberal Democrats senator David Leyonhjelm cautioned against trashing the relationship with Australia's closest ally.
"I caution Mr Shorten and Mr Turnbull and others about dumping on Donald Trump - he may win," he told reporters, while sporting a Johnson-Weld 2016 badge supporting the Libertarian candidates in the presidential race.
"They ought to be very careful about basically destroying our relationship with the possible future president before it's even started."
Liberal senator Chris Back takes a keen interest in American politics because his son's family lives in the US but he wouldn't comment on the merits of either Mr Trump or Democratic candidate Hillary Clinton.
"I don't think it's our business to be commenting on the activities of an election in another country and I certainly don't think it's the role of the leader of the opposition," he said.
Trade Minister Steve Ciobo accused Mr Shorten of "completely junking diplomatic traditions".
But Treasurer Scott Morrison said the Australia-US alliance ran very deep across governments institutionally.
"I would absolutely expect that whoever is elected in the United States that we would continue to have a very strong and special relationship," he told 2GB radio.
"The professional nature of politics would mean that people would just get on with it."
However Mr Morrison was concerned that both the Trump and Clinton campaigns had indicated they wanted to retreat on trade.
Senior Labor frontbencher Brendan O'Connor said Australia's relationship with the US was strong.
"It will certainly be strong enough to withstand any criticism we might have of Donald Trump," he told Sky News.
