FILE - In this Oct. 23, 2015, file photo, Republican presidential candidate Donald Trump speaks at the Trump National Doral Miami resort in Doral, Fla. An overwhelming majority of Republican voters believe Donald Trump would be the GOP’s strongest candidate in a general election, according to a new Associated Press-GfK poll that highlights a sharp contrast between the party’s voters and its top operatives regarding the billionaire businessman’s ultimate political strength. (AP Photo/Alan Diaz, File)

Once, not so long ago, it was great fun to mock the Donald. And it was so easy. He was the short-fingered vulgarian, as the late, great Spy Magazinehad dubbed him.

There was the fake sneer. The naked narcissism. The 18-karat, gold-plated seat belts in his helicopter.

When he decided to actually run for president, it seemed like a Palin-sized gift to those of us who write about politics for a living. And when he shot up to the top of the polls, the joke, it seemed, had gone viral.

The one person in America who couldn’t be taken seriously was suddenly the leading GOP candidate for the most serious job in the world. And Republicans, who had welcomed Trump into the race as a novelty act, were shocked to discover that they had no idea how to get rid of him.

It was irony. Or payback. Or nativism run wild. Or something. Whatever it was, it was certainly politics at its most ugly and also most absurd, which is how Trump has come to lead in the polls for four months now. And no matter how many times Nate Silver insists that the polls tell us nothing about what will happen a few months from now, there’s still the fact that one-third of Republicans say that they would vote for him today.

And there’s this, too: Somewhere along the way, the joke just stopped being funny.

I’m not sure when the end date was, but the day that the terrorists attacked Paris, and the world really got serious, certainly fits. It was around the time that Trump extended his anti-Mexican-immigrant rhetoric to anti-Muslim rhetoric, one minority group apparently being as good to demagogue as the next. And it just gets worse.

In fact, when it comes to fear-mongering, Trump has had a few days that must be unmatched since the time of George Wallace. Here’s the short list: He condoned a crowd of supporters who had roughed up a protester, saying the man had probably deserved it. Trump’s campaign retweeted a fake Tweet citing a fake institute saying that most white murder victims were killed by African-Americans, when, of course, most white people are killed by white people. He said that Obama intends to take in as many as 250,000 Syrian refugees — Trump calls them “strong young men … tough cookies” — when Obama has put the number at 10,000, many of them, just guessing, women and children.

But what’s worse is that it’s not just Trump, who simply goes further — trashing much of the Bill of Rights along the way — than everyone else. It’s also the nearly 30 governors who say they don’t want Syrian refugees in their states. It’s Marco Rubio who goes old school to talk about “clash of civilizations.” It’s Ted Cruz who goes all crusader and says we should set a religious test — Christians only — when taking refugees from Syria. Trump, meanwhile, talks of Muslims having to register, just to be sure that no one could possibly top him. And it goes on and on, in what Michael Gerson calls a “raw and repugnant nativism.”

Trump may have hit his own personal low by taking us back to 9/11, back to a time when George W. Bush was warning against blaming Islam for the terrorist attack. Trump tells how, on that terrible day, he was watching TV as thousands of Jersey City Muslims celebrated when the towers were coming down. Were you watching TV that day? The fact-checkers say it never happened. Do you remember it happening?

Strangely, the only person who briefly remembered the celebrations was, yes, Ben Carson, who said he saw the newsreels. In other words, Trump’s top competitor in the polls said he saw the same thing that never happened that Trump had said he saw that never happened. And so the Carson campaign was once again forced into damage control, saying that Carson had been, well, confused, and noted that the candidate “doesn’t stand behind his comments.” OK, maybe that is funny.

What I did see on TV was George Stephanopoulos grilling Trump on the matter and Trump refusing to back down because the best way to tell a lie is to repeat it for as long as it takes to seem like the truth. But that wasn’t the worst of it.

Not when you’ve got the tough-talking, no-surrender, Jersey boy Chris Christie himself being asked about the Trump statement and you watched as he, uh, hedged. Man, did he hedge, saying he couldn’t remember Muslim celebrations in his state, and “I think if it had happened, I would remember it. But, you know, there could be things I forgot, too.”

Yeah, maybe. But when the history of this campaign is written, it won’t be any problem remembering who stood up and who stood silent. No joke. No joke at all.

Mike Littwin writes for the Colorado Independent (