Donald Trump (Mike Segar/Reuters)

Donald Trump has never been one to shy away from embracing conspiracy theories.  This is the man who suggested that Ted Cruz's father might have been involved in the assassination of John F. Kennedy. Who insisted a malfunctioning microphone was the work of a media determined to keep him from winning. Who spent five years “investigating” whether President Obama is a U.S. citizen. (Turns out he is!) Who suggested that the death of Supreme Court Associate Justice Antonin Scalia might have been the result of foul play. And who speculated about the circumstances surrounding the suicide of longtime Clinton confidant Vince Foster.

On Thursday in West Palm Beach, Fla., Trump — with his campaign reeling from revelations regarding lewd comments he made about women in 2005 and a series of allegations of groping — delivered the latest iteration of his stump speech. It was an address that can be summed up in a single word: “Conspiracy.”

Time and again during the speech, Trump castigated the media, the Clintons and the Clinton-media complex for what he described as a concerted attempt to not only smear him but to disenfranchise the voices of working people across the country.

“For those who control the levers of power in Washington, and for the global special interests, they partner with these people that don't have your good in mind. Our campaign represents a true existential threat like they haven't seen before,” Trump said.

“It's a global power structure that is responsible for the economic decisions that have robbed our working class, stripped our country of its wealth and put that money into the pockets of a handful of large corporations and political entities,” Trump said. 

This is well documented, and the establishment that protects them has engaged in a massive coverup of widespread criminal activity at the State Department and the Clinton Foundation in order to keep the Clintons in power,” Trump said. 

“These attacks are orchestrated by the Clintons and their media allies. The only thing Hillary Clinton has going for herself is the press . . . without the press, she is absolutely zero,” Trump said.

This is a conspiracy against you, the American people, and we cannot let this happen or continue,” Trump said.

Conspiracy theories — and those who ascribe to them — are bulletproof. Anyone who doubts their veracity is seen as part of the “them” in the “us vs. them” dynamic of the conspiracy theorist's world. Of course you would deny that the media and the Clintons are conspiring to get Hillary elected so she can pursue a globalist agenda and destroy American jobs. You just can't see the whole truth. Or maybe you don't want to!

The problem for Trump is that his argument has two major flaws: a) evidence and b) breadth.

On the evidence front, there is precious little. What Trump did in this speech — and what he has continuously done for months in this campaign — is assert a series of serious charges with no actual evidence to back them up. The media and Clinton are colluding? How? Why? When? Where? The New York Times is engaged in a non-journalistic smear campaign? The attorney general's office is involved in a coverup of Clinton's criminal activities related to her private email server?  And everyone but the people who support Trump are in on it.

On the breadth question, even if every person who attended a Trump rally or told a pollster they supported him believed his conspiracy-laden line of thinking, it wouldn't be nearly enough people for him to be elected president in 26 days' time. Trump's base will be for him no matter what; the past few weeks have made that clear. But that base simply isn't large enough to win him the 270 electoral votes he needs. And a message of “everyone is out to get me/us” seems unlikely to me to be compelling to still-undecided voters.

Trump's Florida speech confirms that a bunker mentality has now seized the Trump campaign. It's “us vs. them.” But there are too few “us” and far too many “them” to make it a viable election strategy.