Donald Trump is hammering away in the closing days of his presidential campaign with a claim that doubles as an excuse if he loses on Nov. 8.
The election is "rigged," Trump repeatedly insists, stolen through voter fraud at polling places in big cities such as Philadelphia.
Trump's supporters at his packed rallies cheer when he makes this claim. But their candidate can't back it up with convincing evidence.
Instead, he presents anecdotal accounts of dastardly behavior in past elections.
The most forceful, or farcical, story - depending on your point of view - centers on two numbskulls with one nightstick standing outside a North Philadelphia polling place during the 2008 general election for president.
Welcome back, New Black Panther Party.
Long story short: Two NBPP members wearing black fatigues and berets stood outside a polling place on Fairmount Avenue near 12th Street. One had a Democratic certificate as a poll watcher. The other had a nightstick.
A Republican poll watcher called in a complaint.
Another Republican poll watcher, Stephen Robert Morse, showed up and videotaped a terse but peaceful encounter he had with the NBPP members.
Morse gave that video to Election Journal, a website dedicated to "fraud, cheating, dirty tricks, absurdity and other election news," run by Mike Roman, a former Republican leader of Northeast Philadelphia's 56th Ward.
The video went viral, with more than 1.9 million YouTube views as of last week. It is the Holy Grail of conservative suspicions about voter fraud.
No voter complained about the NBPP members standing in front of the polling place. That doesn't seem to have mattered.
What followed was a political struggle within the U.S. Department of Justice about what to do, as then-President George W. Bush was exiting office and President Obama was taking over the White House. Cases were filed. Cases were dropped.
Fox News played up the NBPP incident for ages.
And here was pro-Trump pundit Kayleigh McEnany explaining his "rigged" rhetoric on CNN last Thursday: "I think he's setting up a scenario where he wants supporters to be vigilant. He doesn't want a scenario where there's New Black Panthers outside with guns, essentially, like, intimidating people from coming into the polls."
The 2008 NBPP video now gives rise to a divergence of opinion about Trump's candidacy.
Morse, who shot the video, still thinks the NBPP members were in the wrong. But he calls Trump's candidacy "sickening," given his controversial comments about women, minorities, and immigrants.
And Morse, who knows the rules of poll watching, says Trump is trying to "stoke a fire" by calling on his supporters at rallies throughout Pennsylvania to come to Philadelphia to observe voting on Election Day.
State law requires poll watchers to be registered to vote in the county where they serve. Trump's supporters, by law, can't just show up for the job in Philadelphia if they're registered in another county.
"Could trouble be brewing? Absolutely," Morse said. "Will Trump try to claim there's voter fraud and other problems that Fox News and others might disseminate and repeat? Of course."
Roman, who disseminated Morse's 2008 video, signed on last week as an "election protection" adviser for Trump's campaign. He declined to comment.
Morse, who moved to England and just received a master's degree in business administration from Oxford University, was a producer on the 2016 Netflix documentary Amanda Knox, about the American woman's troubles while she was an exchange student in Italy: She was convicted of killing her British roommate and spent almost four years in prison before being released.
Morse calls 2008 "a good lesson" in why he has chosen to stay out of politics since then. He still marvels at the power of the video. "There was a nut and I was in the right place at the right time," he said. "There was a camera and I pressed record."