Donald Trump was threatened with castration by an angry New Jersey mobster after the billionaire allegedly tried to seduce the gangster's daughter in the 1980s.

Journalist David Cay Johnston alleges in his book The Making of Donald Trump that the Republican presidential candidate was smitten with the daughter of high-rolling gambler and occasional mobster Robert Libutti while still married to his first wife Ivana.

According to the book, the horse-dealing gangster got wind of Trump's inventions with his daughter Edith Libutti in the late-1980s and told him: "Donald, I'll f---ing pull your balls from your legs."

Before the alleged threat, the book claims, Trump had lavished the mobster's daughter with gifts and thrown her an elaborate birthday party.

The threat was apparently enough to scare The Donald off and Libutti continued to gamble at Trump's Atlantic City tables until he was banned from all New Jersey casinos over his alleged ties to organized crime, according to the New York Daily News.

At the time, Trump denied knowing Libutti.

"I have heard he is a high roller, but if he was standing here in front of me, I wouldn't know what he looked like," Trump told the Philadelphia Inquirer in February 1991, according to the Daily News.