Donald Trump's call for a "shutdown" on Muslims entering the United States has provoked a chorus of disapproval.
World leaders, leading newspapers, and celebrities have used unprecedented language to describe a possible future president: "Racist", "repellent", "ignorant".
For what must have been the first time in history, the leading candidate for the Republican presidential nomination for the US presidency was openly called a fascist by a Democratic contender.
Some, of course, defended Mr Trump. Here are the reactions of some of those he could in theory find himself governing and working alongside in a year's time.
What they said in the US
"[H]e is running for President as a fascist demagogue" - Martin O'Malley, Democratic presidential candidate.
"Donald Trump is unhinged. His 'policy' proposals are not serious" - Jeb Bush, Republican presidential candidate.
"I am hereby barring Donald Trump from entering St Petersburg..." - Rick Kriseman, Mayor of St Petersburg, Florida.
"Trump literally wants to write racism into our law books" - Huma Abedin, aide to Democratic presidential hopeful Hillary Clinton.
"Trump sounds more like the leader of a lynchmob than a great nation like ours" - Nihad Awad, executive director of the Council on American-Islamic Relations (Cair),
"He's an asshole" - Michael Nutter, mayor of Philadelphia.
What they said in the UK, Europe and Canada
How special would the special relationship be under Mr Trump? Here's what UK politicians had to say about his comments.
"Divisive, unhelpful and quite simply wrong" - UK Prime Minister David Cameron.
Mr Cameron's spokeswoman declined to say whether the prime minister would be willing to meet Mr Trump, or whether the Republican might be barred from the UK.
"[A]n attack on democratic values and affront to common humanity" - Jeremy Corbyn, leader of the opposition Labour Party.
"The only reason I wouldn't go to some parts of New York is the real risk of meeting Donald Trump" - Boris Johnson, mayor of London.
Mr Johnson's response to Mr Trump's claim that parts of London were "so radicalised the police are afraid for their lives".
Mr Johnson will no longer by mayor by the time the next US president takes office. So what do the two possible new mayors think of the Republican frontrunner?
"An utterly repellent figure... one of the most malignant figures in politics" - Zac Goldsmith, Conservative candidate for mayor of London.
"He is clearly ignorant" - Sadiq Khan, Labour candidate for mayor of London.
"Mr Trump, like others, stokes hatred: our ONLY enemy is radical Islam" - Manuel Valls, prime minister of France.
"It's something that we can't accept in Canada" - Stephane Dion, foreign affairs minister, Canada.
"We have never been as far removed from what we've just heard in the United States," he added.
What they said in the press
"It is... entirely fair to call him a mendacious racist" - Ben Smith, editor-in-chief, Buzzfeed.
Buzzfeed's editor-in-chief issued a memo to all staff to clear up a style point about referring to Mr Trump, authorising the respected news site's journalists to call the Republican frontrunner a liar and a racist.
"[T]here's nothing partisan about accurately describing Donald Trump", he wrote.
"America's modern Mussolini" - Dana Milbank, the Washington Post.
"Trump's chin-out toughness, sweeping right-hand gestures and talk of his 'huge' successes and his 'stupid' opponents all evoke the Italian dictator's style."
"Who said it, Donald Trump or Hitler?" - London's Daily Telegraph felt comfortable to compare Mr Trump with the Nazi leader.
"I didn't know that Donald Trump was fluent in Nazi" - Bassem Yousseff, Egyptian comedian and former talk show host.
What they said in Donald Trump's corner
Some people must think it was the right thing to say, right?
"Add in every other kind of immigrant and it's perfect!... GO TRUMP, GO!" - Ann Coulter, right-wing pundit.
Ms Coulter's only issue: that Mr Trump's plan did not go far enough.
"NOT endorsing Trump, but support Congressional vote for immediate pause to overhaul vetting process" - Rupert Murdoch
Media mogul Rupert Murdoch appeared to support Mr Trump's idea for a temporary ban on Muslims entering the country, if not endorsing the man himself.
"The Jewish knives are coming out on Donald Trump" - David Duke, former Imperial Wizard of the Ku Klux Klan.
"How come it's against American values to want to preserve the heritage of the country? We're overwhelmingly a Christian country and overwhelmingly a European country," Mr Duke said.
"Everybody else sounds the same" - Rush Limbaugh, conservative talk radio host.
Limbaugh and a cadre of conservative talk radio hosts defended Mr Trump, although none directly supported his Muslim shutdown.
His supporters - when Mr Trump made his announcement, at a rally in South Carolina, it was met with whoops and cheers.