Bill Maher cleared up his reasons for getting into a public squabble with Donald Trump in an interview with Tonight Show host Jay Leno on Tuesday, dismissing Trump's contention that their feud began because Maher was upset Trump wouldn't appear on Maher's Real Time.

"Like I could give a damn if this moron ever does my show," Maher told. "We had a feud because he became a presidential candidate and [became] this insufferable racist. That's why we had a feud: because he was a one-issue candidate, all about the birth certificate."

Besides his fixation on President Barack Obama's birth certificate, Maher also mocked Trump for his $5 million offer for Obama's college records.

"'Cause a black guy getting into college, Jay -- something fishy there," Maher said sarcastically. "So he needed to see some paperwork on that. Well, I needed to see some paperwork on that ferret on [Trump's] head.

Watch Maher explain his feud with Trump, as aired Tuesday on NBC, below.