As even the leadership of his own party tries to deal with Donald Trump's racism – and as jarring as it might be to hear such a term applied to a presumptive presidential nominee, that is by any sensible definition what it is – the strange conga line he's leading rollicks obliviously down the road to Demagogue City, where the facts don't matter, and bigotry is pretty.

In just a few years, Trump has made kooky normal, and race-baiting OK. And millions love him for it.

Does anyone remember the birthers? The people who convinced themselves early in President Barack Obama's first term that he is in fact a Muslim, born in Kenya, posing as an American-born Christian, and therefore not legally in the White House?

They were a cultish bunch, conspiracy nuts really, and provided all sorts of entertaining foolishness until Obama tired of them in 2011 and released the original, long-form version of his birth certificate (it remains on the White House website).

Well, let's not forget: one of the birther movement's leaders was Donald Trump.

"He doesn't have a birth certificate," Trump told Fox News as the birther frenzy peaked. "He may have one, but there's something on that, maybe religion, maybe it says he is a Muslim."

"I am embracing the issue, and I'm proud of the issue," he told MSNBC. "I feel that there is certainly a chance that he was not born in this country. Now, if he were not born in this country, that means he can't be president — it's very simple!"

To lay to rest any question as to President Barack Obama's place of birth, his birth certificate was printed on mugs like these that were sold at the Democratic National Committee in 2013. Trump declared that the document on public record until 2011, Obama's certificate of live birth in Hawaii, meant nothing, and was probably a fraud.

The concurrent 1961 birth announcements in two Honolulu newspapers, he said, were probably placed as a ruse by Obama's parents to have their Muslim foreigner son accepted as an American.

Then, even after the White House published the actual, long-form birth certificate, Trump tweeted this:

"An 'extremely credible source' has called my office and told me that @BarackObama's birth certificate is a fraud."

Now, anyone who has worked in a newsroom has fielded calls from people, usually late at night, who want to share black-helicopter theories.

The usual protocol is to pay attention for a minute or so, cluck sympathetically, and get off the phone.

Now, suddenly, one of them is the Republican nominee for president. And it's not as though he's treating the whole birther business as a long-ago bit of nonsensical political punking.

No, just last year, asked if he still thought Obama was born abroad, he replied: "I don't know. I really don't know."

But of course, he's moved on, and doesn't really want to discuss Obama's birthplace anymore. He sure does want to talk about Muslims, though. All Muslims.

Capitalizing on a mass murder in Florida (in typical fashion, he tweeted Sunday his appreciation to all those who'd offered him "congrats" for "being right about radical Islamic terror"), Trump is insinuating Obama is sympathetic to the likes of ISIS. In other words, the president is secretly a traitor.

Appreciate the congrats for being right on radical Islamic terrorism, I don't want congrats, I want toughness & vigilance. We must be smart! —@realDonaldTrump

"Look, we're led by a man that either is not tough, not smart, or he's got something else in mind," Trump told Fox News after the shootings. "There's something going on. It's inconceivable. There's something going on."

Something. Going. On.

To be clear, this is the president who ordered the assassination of Osama bin Laden, and who has not just continued but stepped up the security policies of his Republican predecessor, especially drone strikes abroad, even on American citizens he's classified as enemy combatants.

But to use Trump's syntax: Listen, folks, we can't forget that he's black, and his middle name is Hussein. I mean, a lot of people still find that strange, believe me. I'm sorry to have to say it, but I refuse to be politically correct, OK?

Now, Trump certainly isn't the first American politician to traffic in innuendo.

But it's been decades since any serious American politician has turned ugly racial generalizations, the sort of thing that would bring conversation at a polite table to an embarrassed silence, into banner slogans. And attracted a following of millions in the process.

Muslim ban

After Orlando, Trump returned to his impossible, unconstitutional, racist (and, apparently, quite popular) notion of a ban on all Muslims entering the United States, to use his phrase.

Republican nominee vows to impose broad ban from areas “with a history of terrorism” 1:17

He called the Orlando shooter, who was, inconveniently, an American-born citizen, an "Afghan."

Citing absolutely no proof, he declared that American Muslims – that of course would be all American Muslims – fail to "turn in the people who they know are bad," mentioning previous shootings by Muslims in a heavily armed country where most multiple shootings are so common that they're barely newsworthy anymore. "They didn't turn them in, and we had death and destruction."

The New York Times, straining under the constraints of its famously understated style, called the remarks "rife with misstatements and exaggerations," reporting that Trump "stretched the truth."

It was, said The Times, "an extraordinary break from the longstanding rhetorical norms of presidential nominees."

Well, that's one way of putting it.

U.S. president take umbrage to Republican's verbal attacks 1:17 Another is that Trump sounds, once again, like one of those newsroom late-night callers who mutter about the CIA broadcasting secret messages to their dental fillings.

Barack Obama, sounding like a real president, rejected the notion of collective guilt, and characterized Trump's response as dangerous on Tuesday.

What Obama can't say is the presumptive Republican nominee is an embarrassment to his own party, and the ultimate IQ test for the American electorate, come November.

It's unreal. But that crazed conga line just keeps dancing.