This could end badly.

Every time Donald Trump starts slipping in the polls, he starts intimating to his followers that there's a conspiracy to rig the election — and a win for Hillary Clinton will be proof that it worked.

He first confessed to being "afraid the election's gonna be rigged" in August. In mid-October, as his campaign melts down in the face of allegations that Trump has serially assaulted women, he's still arguing that there's a conspiracy to rob the election from him and his supporters:

"This is a conspiracy against you, the American people, and we cannot let this happen or continue. This is our moment of reckoning as a society and as a civilization itself."

Often, he doesn't stop there. He's actively encouraged his followers to act as vigilante poll workers: "Go down to certain areas and watch and study make sure other people don't come in and vote five times."

A page on Trump's website allows supporters to "Volunteer to be a Trump Election Observer;" sign up, and you're sent a confirmation email that promises the Trump campaign will do "everything that we are legally allowed to do to stop crooked Hillary from rigging this election."

Donald Trump has spent the last year gleefully taking a sledgehammer to norms of American political campaigns and rhetoric: the importance of judicial independence; the expectation that candidates will release their tax returns; the proposition that when you get called out on a lie, you stop making it; the taboo against openly encouraging violence.

Now it looks like he’s already preparing to take on the biggest, most important norm of all: that when all the votes are counted, and you have fewer of them, you admit it and concede.

You don’t have to believe that Donald Trump is deliberately trying to undermine the foundation of American democracy to understand how dangerous this is. In fact, you probably shouldn’t believe he’s doing this out of malice — given what we know about Trump, it’s more likely he’s engaging in some preemptive butt covering than trying to subvert the democratic process. (That would take work.) But as with so much else that Trump has done over the course of his campaign, he’s tapping into sentiments too powerful for him to control.

A lot of Americans are very ready to believe their opponents steal elections

An underrated truth of American politics is that large numbers of people in both major parties believe that if their side doesn’t win an election, it’ll be because the other side cheated. As Joseph E. Uscinski and Joseph M. Parent wrote in 2014:

Just before the [2012] election, we asked a national sample of respondents about the likelihood of voter fraud if their preferred presidential candidate did not win. About 50% said fraud would have been very or somewhat likely. When asked if someone was using "dirty tricks" in the election, about 85% believed that some candidate, campaign or political group was. These sentiments are not driven by members of one party or the other: Near equal numbers of Republicans and Democrats (between 40% and 50%) said fraud would be very or somewhat likely. Each side believes that if they lose, cheating is to blame, and they believe it about equally.

The 2012 election wasn’t exactly a high-water mark for trust in politics; many supporters of Mitt Romney went into election night believing firmly that polls were "skewed" to disfavor their candidate. But if we’ve learned anything from the Trump phenomenon, it’s that things a lot of people believe in private acquire a whole new power when they’re validated by politicians themselves.

For Trump, of course, the idea that the system is rigged is one of the biggest themes of his campaign. It’s what allows him to break with Republican economic orthodoxy to attack pro-business economic policies ("rigged against workers"). It’s what allows him to talk about the perils posed by Mexican and Muslim immigration to the US from a position of sympathy with the "victims" of crime and terrorism (the idea that Democrats "care more about illegal immigrants than they do about Americans"). It’s what allows him to boil down his attack on his opponent’s character to a single epithet: Crooked Hillary.

In a year when anti-establishment anger is running high, it’s an appealing message. In fact, there are plenty of people — dissident Democrats and Republicans alike — who don’t like Donald Trump per se, but who already believe the Democratic Party rigged the primaries for Hillary Clinton, or that Democrats are trying to rig the general election for her.

Bernie Sanders may have officially endorsed Clinton for the Democratic nomination. But a rump caucus of his supporters continue to insist that her win was illegitimate: that it was engineered by a biased Democratic National Committee, or secured thanks to the anti-democratic actions of superdelegates before the primary campaign started.

Sanders himself hasn’t done much to humor those theories. Donald Trump totally has.

He told Hannity on Monday that the Democratic primary was "rigged against Bernie Sanders with this superdelegates nonsense." On Sunday, in an interview with George Stephanopoulos, he simply implied that Clinton didn’t beat Sanders at all:

DONALD TRUMP: [...] she couldn't beat Bernie, okay? GEORGE STEPHANOPOULOS: Well, she did beat him. DONALD TRUMP: Well, barely. And there's questions even about that, but barely.

Many Republican voters are already worried about voter fraud

Ultimately, there are not a lot of Bernie Sanders supporters who are going to vote for Donald Trump. But there are a lot of Republican voters who are going to vote for him. And the Republican rank and file has been worried about stolen elections — in the form of widespread voter fraud — for several years.

Over the past several days, courts have struck down several state laws that restrict voting: in North Carolina, Wisconsin, Kansas, and Texas. In the eyes of the courts, these laws have (whether intentionally or not) discriminated against nonwhite voters.

But in the eyes of the legislators who passed them, the laws are an important bulwark against voter fraud. (Voter fraud is vanishingly rare, but that doesn’t stop many Republicans from believing it’s widespread.) And when the courts strike them down, they’re simply opening the door for someone to come in and steal the election.

Trump himself has made this connection. When discussing his "rigged election" theory with Bill O’Reilly, he said, "I’m looking at all of these decisions coming on down from the standpoint of identification, voter ID. And I’m saying, ‘What do you mean, you don’t have to have voter ID to now go in and vote?’ And it’s a little bit scary. [...] People are going to walk in, they are going to vote 10 times maybe."

That's the purpose of asking supporters to go to "certain areas" and "make sure" people don't vote five times. The idea that such intimidation — like other restrictions on the vote — might successfully deter people from voting even once doesn't register.

But unlike some of the things Trump says, which have no bearing on standard GOP talking points, this one comes directly from the Republican state officials pushing voter ID laws themselves.

In Kansas, Secretary of State Kris Kobach has said, "There is a significant problem in Kansas and in the rest of the country of aliens getting on our voting rolls. With so many close elections in Kansas, having a handful of votes that are cast by aliens can swing an election."

In North Carolina, the state Senate leader and House speaker have been even more explicit. When the Fourth Circuit Court of Appeals struck down several provisions of North Carolina voting laws last week, they speculated, "We can only wonder if the intent is to reopen the door for voter fraud, potentially allowing fellow Democrat politicians like Hillary Clinton and Roy Cooper to steal the election."

Trump is probably acting out of carelessness, not malice

If Donald Trump were a traditional presidential candidate — loyal to his party and disciplined in his messaging — it would be fair to look at all this and conclude that the Republican Party, led by its presidential nominee, is laying the groundwork to delegitimize a Clinton win in November.

But to be honest, Donald Trump probably isn’t thinking that far ahead. Instead, he seems to be worried he’s going to lose, and so he’s trying to make sure everyone but him gets blamed for it.

The day before Trump started hinting about the election being "rigged," he attempted to raise a stink about the "unfair" scheduling of the fall debates (two of which will happen at the same time as nationally televised NFL games).

And a few days before that — at a rally in Colorado — he blamed his very own supporters for a potential Trump loss:

Trump preemptively blames voters for a loss: "Just in case we don’t make it because you people get lazy and don’t vote, CO's very important" — Alexandra Jaffe (@ajjaffe) July 29, 2016

Yes, Donald Trump really likes winning. But he also likes to have a ready-made excuse when he doesn’t win. As National Review chronicled in March, Trump has a long and ignominious record of blaming everybody else when a Trump venture fails.

Trump seems to be looking for scapegoats for his own loss months before the first votes are even counted: the Democrats, the debate commission, his own voters, even local fire marshals. Taken altogether, it looks less like the efforts of someone preparing to mount a post-election challenge (which, after all, takes a lot of work) than the efforts of someone trying to make sure he emerges from a loss unscathed.

Trump is playing with fire

Whether or not Trump intends to contest the legitimacy of Clinton’s election after the fact, he’s certainly giving license to his followers to do just that. Trump’s followers adore him in part because he says things they’d always believed but had simply been afraid to say; if he stops saying them, they won’t stop believing them. Just ask Bernie Sanders.

Sanders has spent the past few weeks laboring to get his supporters to embrace Hillary Clinton. They’ve been trying to restore her legitimacy as a candidate.

But after some of Sanders’s top aides had spent months reassuring supporters that Sanders really could win the nomination (no matter what they read in the press) — and that when the numbers indicated they were losing, "there’s obviously something wrong with the numbers" — the campaign couldn’t suddenly herd its supporters into the Clinton camp en masse.

Sanders supporters who had convinced themselves that their candidate was robbed of a victory weren’t necessarily going to change their minds just because Sanders said they should. It’s hard to restore legitimacy to a system once you’ve challenged it.

Trump, meanwhile, is spending the weeks before the election telling his followers that the election is so illegitimate that they need to be physically present at polling places to monitor it. That raises the possibility of violence on Election Day. It certainly lays the groundwork for anger and denial afterward — even if Trump himself walks away and takes that nice long vacation he talks about.

Trumpism will absolutely last after Trump. There are too many people who are too willing to feed and guide the anger he’s brought to the surface of politics for it not to.

Before the Republican National Convention, Roger Stone called for Trump supporters to hold "days of rage" in Cleveland. And if anti-Trump delegates managed to prevent him from winning the nomination, Stone said, Trump’s campaign would retaliate.

"We will disclose the hotels and the room numbers of those delegates who are directly involved in the steal," he said on a podcast. "We’ll tell you who the culprits are. We urge you to visit their hotel and find them."

Stone didn’t have to resort to such measures at the RNC. But he’s turning his attention to the general election.

Stone recorded a YouTube video several days ago talking about how Clinton will steal the election. And in an interview with Breitbart last week, he said that Trump’s supporters will "shut the government down" if she wins.

Their inauguration will be a rhetorical, and when I mean civil disobedience, not violence, but it will be a bloodbath. The government will be shut down if they attempt to steal this and swear Hillary in. No, we will not stand for it.

Stone’s imagined bloodbath may be "rhetorical." But he can’t control exactly what Trump’s supporters do with his words. It’s hard to restore legitimacy to a system once you’ve challenged it, and it’s extremely hard to tell people that even if a system is rotten to the core it doesn’t deserve an extreme response.

Donald Trump has often appeared ignorant of the implications of his most provocative rhetoric. When those implications turn into real-life consequences that even he can’t ignore, he tiptoes back from the brink. When he offered to pay the legal fees of anyone who was arrested for restraining anti-Trump protesters, and then a Trump supporter punched a protester in the face, he quietly reneged on his promise.

The problem for Trump is that his supporters believe what he says. If he says a Trump loss means the election has been stolen, there are millions of people prepared to believe it. And on the day after the election, professional provocateurs on talk radio and the internet may be ready to tell them to reject the results of the election and the peaceful transfer of power that comes with it.

Watch: This election is about normal vs. abnormal

UPDATE: This article was originally published before Trump himself made the connection between the "rigged election" and recent rulings on state voter ID laws. But when a politician makes the subtext text, it's usually good to add it to the article.