President Donald Trump’s closing argument for the 2018 midterm elections represents a dangerous escalation of demagogic rhetoric. If it works, things are only going to get worse.

During his presidential campaign, Trump shocked the media and half of the country by declaring Mexicans rapists and outlining an isolationist vision for America. He also covertly sent an “us versus them” message cloaked in the rhetoric of jobs and the economy.

“It used to be the cars were made in Flint and you couldn’t drink the water in Mexico. Now the cars are made in Mexico and you can’t drink the damn water in Flint. What the hell!” Trump yelled at the crowd during his final rally in the early morning hours of Election Day 2016.

It was a promise to his white supporters that he would put them ahead of other groups, like racial and religious minorities and immigrants — the very definition of demagogic politics.

This year, Trump doesn’t bother with fig leaves. He smears minority groups, particularly immigrants, with impunity. This week alone, he made comments, sent tweets, and unveiled policies (some real and some fake) all designed to further dehumanize and demonize his scapegoats.

It looked erratic or even desperate, an irrational response to the reality that Republicans continue to trail in the generic ballot days before the election. It might be desperate, but it’s not irrational. Trump has a good reason to act as he has. It’s his most effective political strategy. And it’s a strategy that demagogues know has to keep ratcheting up to work. And if he’s not stopped now, he’ll only get worse.

“Every demagogue acts voluntarily and through choices. They are not how they are painted; they are not creatures of their own appetite, irrational and out of control,” said Michael Signer, a professor at the University of Virginia who has written extensively on demagogues.

“They tend to be extremely opportunistic and shameless and ruthless political actors.”

Demagogues must demagogue

Trump’s nonplussed response to recent episodes of violence baffled the media, from the murder of a Washington Post reporter in Turkey to a spate of politically motivated mail bombings to a rampage at a synagogue. The press desperately hoped to hear him apologize. His supporters didn’t.

As Patricia Roberts-Miller explains in her book, Democracy and Demagoguery:

It may be counterintuitive, but the charismatic leadership relationship is strengthened by the leader behaving erratically, making what might appear to be irrational arguments, judging situations quickly without much information (especially without expert advice), and making hyperbolic claims (especially about his or her own achievements and, oddly enough, health). Followers don’t expect leaders to be responsible for what they say...their irresponsible behavior is part of their power. Their use of hyperbole and tendency to be unfiltered in speech are taken to signify their passionate commitment to the in-group.

Trump has zigzagged across the country in recent weeks, whipping up crowds by calling immigration a “crisis” (it’s not) and claiming a caravan of asylum seekers thousands of miles from the border are planning an impending “invasion” (they’re not).

From the West Wing on Thursday, he spouted old racist tropes about immigrants and foreigners. They bring “big medical problems before they get here.” There are “young men, strong men,” who are joining caravans of asylum seekers. Women should fear them.

Perhaps Trump’s lowest point was when he released a campaign video so racist that it’s been called worse than Willie Horton by political historians.

Trump’s message is growing increasingly extreme. Like all demagogues, he has no choice but to continue to ratchet up his worst words and worst behavior. While the media and other political observers struggle to see anything but a meltdown, his supporters see exactly what they want to see. They don’t support him in spite of his behavior. They support him because of it.

There are signs Trump knows what he’s doing

Trump’s approval numbers nationally are underwater. But among Republicans, 89 percent approved of the job he’s doing, according to Gallup’s most recent poll.

Meanwhile, his supporters say they believe his line that he’s not responsible for extreme rhetoric in politics or a sense of division in American life. A new Morning Consult/Politico poll found that 80 percent of Republicans agree with Trump’s recent claim that the national media has done more to divide than unite the country since Trump took office.

Trump himself has refused to take any responsibility for his language, particularly at rallies where crowds jeer immigrants, Democrats, and other Trump dissenters. “Well, I think I’ve been toned down, if you want to know the truth. I could really tone it up,” Trump said during the week that prominent Democrats he had attacked were being sent bombs in the mail. The day FBI agents arrested a suspect, one of Trump’s crowds chanted, “Lock her up,” in response to a reference to Hillary Clinton.

In a moment of presumably accidental candor, Trump did concede he often says what he wants, whether or not it’s true. “Well, I try. I do try ... and I always want to tell the truth. When I can, I tell the truth,” Trump said.

“The president’s rhetoric has helped to shift discourse norms in our country such that it is more acceptable among more people to denigrate and attack other groups of human beings,” Susan Benesch, the director of Dangerous Speech Project, told the Washington Post. “People feel emboldened to chant those things publicly, which is a specific example of a shift in public discourse in the country.”

Trump will only get worse

The challenge for demagogues is they don’t have much room to reposition themselves. They can’t start capitulating to the media, apologizing for, say, inspiring someone to mail bombs to his political enemies. They can’t start trying to work on policy with experts and release reasonable plans that take many interests into account — that’s the very opposite of why he’s supported. Demagogues draw a line between themselves and supporters and their enemies. There is no ground for compromise.

That leaves them to yell louder and with more malice.

“Sometimes it can be an act of desperation, and sometimes it can be an act of pure entrepreneurship,” said Steven Levitsky, a Harvard professor and co-author of How Democracies Die. “In the US, it’s closer to an act of desperation. Trump has argued pretty consistently that Republicans, as constituted, know that they’re in a fair amount of electoral trouble in the medium term. They’re playing dirty because they’re trying to grab what they can now.”

A sustained resistance has challenged Trump since the day after his inauguration, when millions of women led marches in opposition. Activists kept up the fight, challenging a travel ban with public assembly and challenging Congress on a health care repeal effort. They did not win every battle, but they showed it is possible to use the rights guaranteed by our system of government to hold leaders accountable.

The question is, which force will win on Tuesday?

“There’s a similar wave of activism among rank-and-file Americans who are repulsed by what they’re seeing,” Signer said. “Trump is seeing that, and it does alarm him, and he has responded by doing more of what he came into office doing, which is more of the demagogue stuff. You really do have two tsunamis colliding into one another.”

“This is one of, if not the greatest, tests constitutional democracy has been through.”