Donald Trump smells a far-reaching conspiracy.

With fewer than 100 days until Election Day, the Republican presidential nominee’s campaign has posited a simple and nefarious explanation for recent damaging stories about intra-party turmoil over Trump’s feud with Gold Star parents, his deteriorating standing in national and swing-state polls, a positive U.S. jobs report in July, and his wife’s plagiarism: The “Clinton machine” is orchestrating them all.

Last week, Trump took it a step further by suggesting, without evidence, that Democratic nominee Hillary Clinton and her allies may steal the election.

“What Trump has revealed is that there are parts of the Republican base that are not connected to the mainstream of the Republican Party, and those folks seem susceptible and receptive to conspiracy theories,” said Mark Fenster, a law professor at the University of Florida and author of the 2008 book Conspiracy Theories: Secrecy and Power in American Culture.

Fenster said Trump has been the most successful national candidate since at least World War II when it comes to exploiting conspiracy-minded proclivities.

Trump has long dabbled in unsubstantiated conspiracy theories. He rose in GOP circles in 2011 questioning whether President Barack Obama is a natural-born citizen (the president was born in Hawaii). This year, Trump suggested rival Ted Cruz’s father was linked to John F. Kennedy’s assassination, posited something untoward about Supreme Court Justice Antonin Scalia’s death, and revived (long-debunked) claims that the Clintons were involved in the suicide of White House aide Vince Foster.

‘Another Clinton Narrative’

A strong jobs report released by the government on Friday—255,000 jobs added in July—prompted the Trump campaign to suggest the market optimism was a Clinton concoction. “The economy the media and the Clinton Machine is describing is an economy that doesn't exist for most Americans,” said Trump adviser Stephen Miller.

On Trump’s war of words with the parents of a slain Muslim U.S. solider, campaign chairman Paul Manafort told Fox News, “The turmoil—this is another Clinton narrative that is put out there and the media is picking up on.”

The rhetoric plays to the misgivings of many Trump voters, a disproportionately older, white, and working-class group that harbors deep disaffection for political elites and institutions they blame for their downward economic mobility and for failing to stop demographic trends that are making the U.S. less white. Recent surveys suggest Trump is failing to expand his appeal beyond his core base.

A Washington Post/ABC News poll published Sunday found Clinton with an 8-point national lead over Trump among registered voters, a margin larger than both of Obama’s victories. Trump’s dominance among white men and whites without a college degree was offset by poorer showings with other factions. Clinton led by 1 point among white women (a group Obama lost by 14 points in 2012), by 6 points among college grads (a group Obama lost by 6 points in 2012), and by 57 points among non-white voters (a group Obama won by 63 points in 2012).

“Trump is not showing me he wants to be a serious candidate. It’s like he’s taking the nomination and running everything into the ground,” said Tom Davis, a former Republican congressman from Virginia who described himself as undecided in the November election. He said Trump has potential to broaden his coalition, but “to date he has not shown the attributes of a leader, which is a consensus-builder in your own coalition, let alone the country.”

Recent suggestions of a secret Clinton plot seem to date back to the Republican convention, when Manafort told reporters the Clinton campaign spread the story that sparked an uproar over passages in Melania Trump’s speeches that were lifted from Michelle Obama’s 2008 speech. It was “once again an example of when a woman threatens Hillary Clinton, how she seeks out to demean her and take her down,” he said. (The similarities were first posted online by Twitter user Jarrett Hill, and the Clinton campaign denied spreading them.)

‘Rigged’ Election

When it comes to the presidential debates, Trump hasn’t committed to participating, raising the prospect in late July that Clinton and the Democrats were trying to “rig” them by lowering viewership, calling it “unacceptable.” The presidential debate commission said it chose the three debate dates carefully, aiming to minimize conflicts with big televised events.

Last Tuesday in Ashburn, Virginia, Trump told a crowd that he was running against a “rigged press” and a “dishonest machine” that wouldn’t hold Clinton accountable for her transgressions.

And last Monday, Trump made the extraordinary move of raising the specter that the election would be stolen from him. “I'm afraid the election's gonna be rigged, I have to be honest,” Trump told a crowd in Columbus, Ohio.

His campaign has no evidence to support his claim, and experts say rigging a U.S. national election would be exceedingly difficult, if not nearly impossible. After Obama dismissed the notion as “ridiculous,” Manafort defended the claim Friday, saying on Fox News that the president came from the “Chicago machine” and arguing that “if you’re relying on the Justice Department to ensure the security of the elections, we have to be worried.”

Fenster said that while conspiracy theories have long been an underbelly of U.S. politics, Trump’s attack on the legitimacy of the election was unique and “troubling.”

“The worst possible scenario here would be one in which no matter how the election turns out—suppose Clinton wins in a walk, or the race tightens—Trump refuses to accept it,” Fenster said. “Or maybe Trump accepts the results but his supporters, particularly the more extreme ones, refuse to accept it. That seems deeply problematic.”

He likened it to a scenario in which Al Gore could have refused to concede after the contested 2000 election, or in which former President Bill Clinton refused to vacate the White House on the belief that George W. Bush stole the election.

Democrats see in Trump’s words an attempt to delegitimize a potential Clinton presidency. Some worry that Trump allies in conservative media would buttress the contention of a stolen election and that many Americans would believe it.

“Trump believing and convincing his supporters that the election was rigged matters a lot,” former Obama senior adviser Dan Pfeiffer said on his podcast, Keepin' It 1600. “Because when you add with the ‘lock her up,’ ‘Hillary Clinton's a crook,’ [FBI Director] ‘Jim Comey’s in the pocket of the Clinton campaign’—it’s all about de-legitimizing Hillary Clinton’s first term. To create a set of excuses for why Republicans should oppose the most basic governing responsibilities.”