Leslie Cockburn, a Democratic congressional nominee in Virginia, accused her Republican opponent, Denver Riggleman, on Sunday of campaigning with white supremacists and being the author of Bigfoot-themed erotica.

Yes, you read that correctly.

Cockburn’s accusation, which was made in a tweet Sunday night, prompted a frenzy of jokes on social media and a denial from the Riggleman campaign.

In an interview Monday, Mr Riggleman said he was writing a book about people who believe in Bigfoot but denied that it contained any erotic content. He said any eyebrow-raising images of Bigfoot on his social media accounts were a result of “a 14-year practical joke between me and my military buddies”.

Here is a quick guide to what will hopefully be the only Bigfoot-related story of the 2018 midterm elections.

How did this start?

Cockburn and Riggleman are competing for a seat in Virginia’s 5th Congressional District. The district includes Charlottesville, the site of 2017’s “Unite the Right” rally, a violent melee in which one person was killed and more than two dozen others injured when a man drove a car into a crowd of counter protesters.

The House race there was upended in May when the Republican incumbent, Tom Garrett, said he would not seek re-election so he could instead focus on receiving treatment for alcoholism. Mr Riggleman, an Air Force veteran and businessman, won the Republican primary to run as his replacement.

Since then, Cockburn has made an effort to link Mr Riggleman to elements of the far right, including Corey Stewart, the Republican nominee for US Senate in Virginia. Mr Stewart, a Minnesota native, has defended the confederacy and praised (then disavowed) white nationalists.

Cockburn began her tweet Sunday by referring to Mr Riggleman as Mr Stewart’s “running mate” (he is not; senators don’t have running mates). She also said he had been “caught on camera campaigning with a white supremacist”. Mr Riggleman denied the accusation.

Where does Bigfoot factor into all this?

Bigfoot enters the picture in the second half of Cockburn’s tweet.

“Now he has been exposed as a devotee of Bigfoot erotica,” she wrote of Mr Riggleman. “This is not what we need on Capitol Hill.”

Ms Cockburn included an image that Mr Riggleman said was taken from his Instagram account. It was a naked drawing of Bigfoot, the mythical north American woodland creature, with a black “censored” bar hanging from his crotch to his knees. He held his arms aloft, as if to shrug.

Ms Cockburn, whom Republicans have accused of anti-Semitism for a book she wrote on the US-Israel relationship, declined to be interviewed. But her campaign spokeswoman, Louise Bruce, said in a statement that voters “deserve to know the true character of anyone who is asking to be sent to Congress to represent them”.

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Mr Riggleman and Bigfoot go back a long way.

In an interview, he said he did not believe in Bigfoot but had been interested in the topic since he was a child. When he was 10, he said, his grandfather abruptly ended a walk they were on because he “saw something mighty peculiar that was hairy and large” in the woods. (Mr Riggleman does not claim to have seen anything himself.)

That childhood interest led to his participation in an ESPN article more than a decade ago that described his participation in a Bigfoot hunt in West Virginia.

He has participated in the writing of a book on the subject, Bigfoot Exterminators, Inc.: The Partially Cautionary, Mostly True Tale of Monster Hunt 2006. It was authored with ESPN writer Don Barone and described another Bigfoot hunt in the Adirondack Mountains of New York.

Mr Riggelman explained his relationship to Bigfoot, and some theories about the creature, in a video posted Monday to the YouTube channel of The Conservative Review.

The image was a joke, but the book is real, he says

Monster-themed pornography, including material involving Bigfoot, does exist. But Mr Riggleman said his work on the subject had not been pornographic.

“I didn’t know there was Bigfoot erotica, even with all my Bigfoot studies,” he said. “I thought this was such a joke that nobody would ever be dumb enough to think that this was real, but I guess her campaign did.”

Mr Riggleman says the whole thing is a joke that has been misconstrued by Ms Cockburn. The naked drawing of Bigfoot that she tweeted was a gag that was sent to him by friends – although it was a reference to the title of a real second Bigfoot book that he says he is writing: The Mating Habits of Bigfoot and Why Women Want Him

He describes the book as “a sort of joke anthropological study on Bigfoot believers”.

A second image tweeted by Ms Cockburn also referenced the book. It showed a censored, naked Bigfoot, but unlike in the first drawing, a photo of Mr Riggleman’s grinning face sat, digitally superimposed, atop the creature’s hairy shoulders.

“I have a sense of humour,” Mr Riggleman said. “I’m not going to apologise for personality.”