In the 1989 film "Back to the Future Part II," Marty McFly travels from the '80s to the future: Oct. 21, 2015. Today.

It's on the 21st that evil Biff Tannen steals McFly's time machine, travels to 1955 and gives his younger self a 2015 sports almanac that brings him a gambling fortune. When McFly returns to 1985, Tannen is obscenely rich and powerful. He lives in a tower on top of a casino and has a blond combover.

It's long seemed as though filmmakers based rich Biff on Donald Trump -- and screenwriter Bob Gale finally confirmed as much on Wednesday in an interview with The Daily Beast's Ben Collins.

"You watch Part II again and there’s a scene where Marty confronts Biff in his office and there’s a huge portrait of Biff on the wall behind Biff," Gale said, "and there’s one moment where Biff kind of stands up and he takes exactly the same pose as the portrait? Yeah."

Fortunately for presidential candidates running against Trump, the film also demonstrates how he can be defeated, because Biff turns out to be a loser.

The first thing a candidate has to do to beat Trump is escape from his penthouse to the roof of the Trump Tower. Then stand on the edge of the roof and stall for a minute. Jump -- Trump will be stunned. He'll approach the edge of the building, only to be struck in the head by the gull-wing door of the flying Delorean that breaks the candidate's fall. Then it's a simple matter of traveling to 1955 and intercepting Trump's inherited wealth and connections. Good luck!