Christine O'Donnell, the Republican vying for former-Sen. Joe Biden's seat in Delaware, has said she doesn't believe in evolution.

"You know what — evolution is a myth," O'Donnell said during a 1990s appearance on Bill Maher's "Politically Incorrect."

A short video clip — aired Friday night during Maher's new HBO show, "Real Time" — shows a much younger O'Donnell sparring with the host over Darwin's well-accepted theory.

Maher responded, "Have you ever looked at a monkey?"

"Well then, why aren't monkeys still evolving into humans?" O'Donnell asks.

"It takes a long time," Maher answers.

It's not the first time O'Donnell has made potentially embarrassing remarks on Maher's old show. 

Last week, the comedy host aired another "Politically Incorrect" clip from the 1990s in which O'Donnell says she's "dabbled in witchcraft." 

"I hung around people who were doing these things," O'Donnell says in the 1999 episode. "I'm not making this stuff up."

Backed by Sarah Palin and nationally funded Tea Party groups, O'Donnell shocked the GOP establishment earlier this month by defeating long-time Rep. Mike Castle in Delaware's Republican primary.

While energizing the Tea Party, the upset has angered many GOP loyalists who were banking on a likely Castle victory in November. Instead, the seat is now expected to go to the Democrats. 

Maher, for his part, is vowing to release more footage unless O'Donnell appears on his show.

"If you don't come on this show, I'm going to show a clip every week," Maher warned. "I'm the only one who has them."