Meghan McCain: Rick Santorum's Gay Marriage Opposition 'Dated' And 'Gross' (VIDEO)

Meghan McCain, daughter of Sen. John McCain (R-Ariz.), criticized Republican presidential candidate Rick Santorum for his opposition to gay marriage Friday on MSNBC .

"There's a difference between being against marriage equality and then equating same-sex marriage to bestiality," she said, referring to Santorum's 2003 interview with the Associated Press in which he linked homosexuality and "man on dog" sex.

"I mean it's so dated and it's so gross," McCain continued. She repeated that she supports gay marriage.

She added, regarding Santorum's views, "It's far off the course of mainstream America, and it's enough for me just to say goodbye." She also predicted that the more people know Santorum, the less they will like him. "If you nominate someone like Rick Santorum, I guarantee he will lose," she said.

Santorum doubled down on his opposition to gay marriage Tuesday at a campaign appearance in Concord, N.H., comparing gay marriage to polygamy. Meghan McCain approved of the college student who grilled Santorum on the issue.

She praised Republican presidential candidate Mitt Romney, who her father endorsed Wednesday, saying he has a "fantastic personality off-camera." Romney also opposes same-sex marriage.

About her father's opposition to gay marriage, she said, "My father is hopefully going to be the next one I can work on, and he's sort of coming around." She added, "he's 75 years old, so it's a bit different."