By now, we know that President Trump is a lying [1] demagogue. Since this is not said often enough, he has been allowed to routinize lying and enshrine the vilest forms of divisiveness as a normal part of our politics.

Lies do not deserve deference just because a president tells them.

We thought that the media learned during Joe McCarthy’s heyday that “We report the lies, you decide” is not a responsible approach to journalism. Trump’s egregiousness requires everyone to take a refresher course in the lesson of McCarthyism.

At the same time, just calling out deceit is insufficient. It is essential as well to understand why Trump tells particular lies at particular moments and to be hardheaded in judging how effective they are. This is a precondition to turning back the smears and the falsehoods.

Trump’s address Tuesday at a Nashville rally was a lollapalooza of deception. He kept the fact-checkers busy. PolitiFact [2] raised doubts about 15 of his statements and flatly rated 10 of them as “mostly false,” “false,” or “pants on fire.”

But two passages are worth special attention.

“They don’t want the wall, they want open borders,” Trump said of Democrats. “They’re more interested in taking care of criminals than they are in taking care of you.”

For good measure, he referred to the House Democratic leader as “the MS-13 lover Nancy Pelosi,” linking her to the brutal gang whose members Trump continues to call “animals.” He even pumped up the crowd to shout out the word.

As a factual matter, “open borders” are not a policy supported by anyone except a handful of libertarians. The “taking care of criminals” line and the slandering of Pelosi have become so common they are barely noticed. Republicans on the ballot this fall should be asked if they see Pelosi as an “MS-13 lover,” and if not, whether they will denounce Trump for saying such a thing. I am not holding my breath.

Yet sometimes Trump engages in a perverse form of transparency. He signaled clearly that the whole point of his screed during which he also re-upped his claim that Mexico would pay for his border wall—was about the midterm elections. Immigration, he said, is “a good issue for us, not for them.”

Why immigration? It’s not the central concern of most voters. A Gallup [3] survey in May found that 10 percent of Americans listed it as the most important problem facing the country. And Trump’s wall is not popular—in a recent CBS News poll [4], 59 percent of Americans were against building it. 

But currently, Trump and the Republicans aren’t focused on the majority of Americans. They are petrified that their own loyalists do not seem very motivated about voting in November. 

Another May Gallup study [4] found that just 26 percent of Americans strongly approved of Trump’s job performance, compared with 41 percent who strongly disapproved. Only George W. Bush in 2006 (at a time of rising impatience with the Iraq War and dismay over his handling of Hurricane Katrina) and Richard Nixon in 1974 (at the height of the Watergate scandal) exceeded Trump’s level of strong disapproval. The midterm elections in those years were disastrous for the GOP.

Trump and his party feel they need to screech loudly to get their side back into the game, and attacking immigration (going back to Mexican “rapists”) is the signature Trump talking point. Voters who listed immigration as a motivating factor in 2016 backed him over Hillary Clinton by nearly 2-to-1. And the CBS poll found that while Democrats and independents overwhelmingly opposed Trump’s wall, 78 percent of Republicans supported it.

Republican House candidates are following Trump’s lead, according to a USA Today study [5] published Tuesday, “blanketing the airwaves with TV ads embracing a hard line on immigration.” By contrast, health care was the topic most invoked in Democratic spots. The GOP’s emphasis may shift some after the primaries are over, but Republicans seem to know that wedge issues are more useful to them than their record.

Political polarization has many sources, but the prime cause of it now is the president himself. Polarization defines Trump’s survival strategy and it means that demagoguery—toward immigrants, toward crime, toward Robert Mueller’s probe, toward dissenting NFL players, toward anyone who takes him on—is what his presidency is all about. 

What thus needs exposing is not simply Trump’s indifference to the truth but the fact that he depends upon the kinds of lies that will tear our country to pieces.