A 1958 episode of the television western Trackdown features a con artist named Trump who wants to build a wall to protect a town from destruction. From the Classic TV Archive:
Walter Trump, a confidence man, puts on a long robe and holds a tent meeting in the town of Talpa. He tells the townspeople that a cosmic explosion will rain fire on the town and that he is the only one that can save them from death. Ranger Hoby Gilman attempts to prove Trump is a fraud.
And a bit of dialog from the episode:
Narrator: Hoby had checked the town. The people were ready to believe. Like sheep they ran to the slaughterhouse. And waiting for them was the high priest of fraud.
Trump: I am the only one. Trust me. I can build a wall around your homes that nothing can penetrate.
Townperson: What do we do? How can we save ourselves?
Trump: You ask how do you build that wall. You ask, and I'm here to tell you.
"Trackdown Shakedown" (Snopes, thanks David Steinberg!)