In a shocking new interview on the Tyra Banks Show, Levi Johnson, the baby daddy of Sarah Palin's grandson, revealed that the Alaska governor likely new that her daughter Bristol was having sex with him before she fell pregnant.

"I'm pretty sure she probably knew. Moms are pretty smart," said Johnston, 18, in an interview which will air Monday.

Johnston also commented that he and Bristol practiced safe sex "most of the time."

The news of Bristol's pregnancy age age 17 couldn't have come at a worse time for Sarah Palin, who was in the middle of a campaign with John McCain to win herself the position as Vice President of the United States. The news broke just days after McCain announced her as his new running mate.

Palin said at the time she was stunned by her daughter's news:

"When Bristol and Levi first told us the shocking news that she was pregnant, to be honest, we all at first looked at the situation with some fear and a bit of despair. Isn't it just like God to turn those circumstances into such an amazing, joyful blessing when you ask Him to help you through?"

Levi and Bristol were engaged to be married, but recently broke up. Their child, Tripp Easton Mitchell Johnston, was born on December 27, more than one month after Palin lost her bid for a spot in the White House.

Johnston's mother, Sherry, will also appear in the show airing Monday. She says that they were under a gag order by the McCain camp during the presidential race:

"We were supposed to say that all questions need be brought up to the McCain campaign. Other than that we had to say no comment."

Johnston also revealed that he had been sharing a room with Bristol at the governor's home before their recent break-up. He had moved in about one or two weeks before Bristol gave birth.

In the inteview, Levi and Sherry dish on the Palin family, the campaign, his relationship with Bristol, and the "real reasons" that they parted ways.