Donald Trump has a long list behind him of people, places and countries he has offended in his race to the White House.
But many world leaders and politicians have not let diplomacy stop them from having their say on Mr Trump's policies and opinions and what a President Trump would mean for the world.
"I caution Mr Shorten and Mr Turnbull and others about dumping on Donald Trump - he may win.
"They ought to be very careful about basically destroying our relationship with the possible future president before it's even started."
Opposition leader Bill Shorten. (AAP) Source: AAP
Mr Shorten has also described Mr Trump as , a comment Prime Minister Malcolm Turnbull said was an "ill-judged remark".
"You can imagine how Australians would feel if an American president were to describe one of our prime ministerial aspirants as barking mad," he told reporters in Brisbane.
"You can imagine the ill-will and resentment that would create in Australia."
"The proposal to build the wall, and to believe that Mexico could and would pay for it, is outrageous. What I know is that Mexico will not pay a single cent if they want to build a wall on that side of the border."
"I was very clear - in private and in public - in stressing that in Mexico we feel offended and hurt by his pronouncements about Mexicans. In his campaign speeches, Trump has not treated us like partners, nor as allies, based on a distorted picture of Mexico and its people."
“You have a fantastic opportunity here: You can beat the pollsters, you can beat the commentators, you can beat Washington and you’ll do it by doing what we did for Brexit in Britain—we had our own people’s army of ordinary citizens. Who convinced and inspired people to vote for change.
"Anything is possible if enough decent people are prepared to stand up against the establishment.”
UN High Commissioner for Human Rights, Zeid Ra'ad Al Hussein. (AAP) Source: AAP
"At the very least, you expect that people running for public office will know enough of historical experience and the suffering of those who are going to fall in the crossfire if this escalation in rhetoric and passion eclipses calm and rational thinking about this."
"It's grossly irresponsible, given what the aim of the extremists is, to play into their hands at the expense of those who themselves - the vast majority of ordinary Muslims - would be viewed as eligible targets by these extremist groups."
"A person who thinks only about building walls, wherever they may be, and not building bridges, is not Christian."
“If I were American, I would vote Donald Trump. But may God protect him!”
"I'm conflicted by that because my natural inclination would be to see a Republican in the White House, but I tremble at the thought of Trump being president. There's an instability about him that bothers me."
London Mayor Sadiq Khan. (AAP) Source: AAP
"If Donald Trump becomes the president I’ll be stopped from going there by virtue of my faith, which means I can’t engage with American mayors and swap ideas.”
"His election would complicate relations between Europe and the United States."
“It turns out that Trump is not the rough-talking, screwy, ignorant candidate they say he is, but is actually a wise politician and a prescient presidential candidate.”
Zimbabwean President Robert Mugabe. (AAP) Source: AAP
“I think his remarks are divisive, stupid and wrong. I think if he came to visit our country he’d unite us all against him.”
"A successful politician would not make such statement, as there are millions of Muslims living in the US. I don’t know whether or not he’ll win, but let’s suppose he won. What will happen? Will he set aside all relationships with Muslim countries? A politician shouldn’t talk like this.”
UK Foreign Secretary Boris Johnson. (AFP) Source: AFP
"I have never seen in my lifetime, or in modern political history, any presidential candidate trying to discredit the elections and the election process before votes have even taken place. It's unprecedented.
"That is both irresponsible - and, by the way, it doesn't really show the kind of leadership and toughness that you'd want out of a president. You start whining before the game's even over?
"If, whenever things are going badly for you and you lose, you start blaming somebody else? Then you don't have what it takes to be in this job.
"I'd advise Mr Trump to stop whining, and go try to make his case to get votes."
“Let's be clear, Donald Trump is an idiot. I have tried to find different, perhaps more parliamentary adjectives to describe him but none was clear enough. He is an idiot."
“Trump’s remarks do not show a sense of introspection on what their results would bring about; he does not know the gravity of what he says.”
Prime Minister Malcolm Turnbull. (AAP) Source: AAP
"I try to avoid being a commentator on Australian politics, let alone outside of Australia, but I have no doubt the American people will make a very wise choice in November," is the most he has ever said publicly.
However, Deputy Prime Minister and Nationals leader, , has described Mr Trump's political positions as "cruel and nasty".
