"I was so traumatized I never saw another horror film," Ginsberg said. "Werewolves haunted me."
In a sense, they haunt him still.
In 1973, Ginsberg wrote and directed "The Werewolf of Washington," a movie in which a White House press secretary played by Dean Stockwell is transformed under the full moon into the titular creature and kills the president's enemies.
"The Werewolf of Washington" was the second film Ginsberg made. It was also the last.
"I've had a love-hate relationship with this film," the octogenarian told me on the phone recently from his apartment in Manhattan. "It didn't do much for my career, to say the least."
The son of a garment worker, Ginsberg went to Columbia University. After he graduated, he was determined to write the Great American Novel.
"I couldn't get past the Great American First Sentence," he joked.
Ginsberg got a job with NBC News, shooting and editing documentaries. In 1969, inspired and influenced by Fellini and Antonioni, he made a movie called "Coming Apart." Shot in black and white, it chronicles the mental breakdown of a psychiatrist (a young Rip Torn) who has installed a hidden camera in his apartment.
"Coming Apart" was raw and frank (there's an orgy scene) — and divisive.
A few years later, one of that film's producers asked Ginsberg whether he had anything else up his sleeve. As scandal was starting to engulf the Nixon White House — but before Watergate had exploded — Ginsberg went to New York's Fire Island and in 10 days wrote "The Werewolf of Washington."
Said Ginsberg: "I came back and the [producer] said, 'Are you out of your mind? This is an attack on the president. The script is yours. Don't ever show up here again.' "
Another producer and some of Ginsberg's friends stepped in to fund the movie, shot on a shoestring budget of $100,000. Somehow, they were able to get veteran actor Stockwell to star. His career, Ginsberg said, "had fallen into eclipse at that time. He loved the script."
The movie was shot in about four weeks, primarily around Glen Cove, on Long Island. The steps of the Brooklyn Borough Hall stood in for those of the U.S. Capitol, where (spoiler alert!) a Black Panther is killed by the werewolf. A tiny bowling alley in a church stood in for the beloved lanes Nixon built in the White House.
Ginsberg traveled to Washington with Stockwell for a single day to shoot some exteriors, including outside the Sans Souci restaurant.
"It was the watering hole for the bigwigs," Ginsberg said.
Stockwell is a real trouper in the movie, biting into the role with abandon. Still, when "The Werewolf of Washington" opened in October 1973, it was greeted with harsh reviews.
"That was a little too rough," Ginsberg said. "It really broke my spirit for a while, to put that much effort into something and get the film you wanted to make with no response. At least with the first film, half were saying 'masterpiece' while the other half were saying, 'Forget this thing.'
"To make two films like this really tires you out," he said. "It ruined my career. . . . I had made two films and made no money."
Ginsberg continued to write screenplays. They would be optioned but not made. (One, called "Stuck," was about 10 film critics trapped in an elevator on the way from a screening.) He paid the bills as a film editor. He's worked on three Academy Award-winning documentaries.
Ginsberg said the only money he made from "Werewolf" was $2,000 he got for writing the script. He didn't own the film's copyright. Neither do the original producers anymore — they let it lapse — which is why you can find the entire movie on YouTube.
"When the film came out in 1973, German television bought it," he said. "In those days, if a TV station in Germany bought a film, they would show it once a week. Everybody growing up in Germany knows my film. Of course, here they don't."
I'd love to see "The Werewolf of Washington" on a big screen. Whaddya say, AFI Silver?
Before we hung up, I asked Ginsberg if he thought Donald Trump's presidency would make a good movie.
"Absolutely," he said. "But it's almost less funny. It's much scarier now."