After all, she's about to turn 18 now and is a big supporter of.
"What I don't like about the ad is its fear-mongering," Knowles told ABC's "Good Morning America Weekend Edition" on Sunday. "I think it's a cheap hit to take. I really prefer Obama's message of looking forward to a bright future."
The well-known Clinton ad aired in Texas before last week's vote and implied a lack of experience on Obama's part. It showed an exterior of a Colonial-style home and old stock footage of Knowles sleeping in bed. A narrator describes a phone ringing in the White House: "It's 3 a.m. and your children are safely asleep. Who do you want answering the phone?"
Clinton won the Texas primary by a 51-47 percent margin.
Knowles said she didn't see the ad until Jon Stewart lampooned it Thursday on "The Daily Show." Her brother noticed it was her, and the family replayed the commercial on their digital recorder to be sure.
"They were parodying this ad, kind of poking fun at it," Knowles said. "My brother was like, 'Is that Casey?' And we just erupted. Sure enough, it's me."
The file footage was originally shot for a railroad company advertisement. The Clinton campaign bought it from Getty Images.
Knowles, a senior at Bonney Lake High School who turns 18 next month, has been campaigning for the Illinois senator. She attended his rally at Seattle's KeyArena on Feb. 8. Her mother, Pam, told The News Tribune of Tacoma that Casey cried and trembled after shaking the candidate's hand.
The next day, she was a Democratic precinct captain for the state's caucuses. If she plays her cards right, she could go to the national convention.
Not to mention that she could be in another ad. After her identity became known, Obama's campaign contacted her.
"I mentioned that we should make a counter ad, me and Obama, against Hillary," she said. "They thought that was really funny. They actually might take me up on it."
That said, Knowles said she plans to vote for whichever Democrat wins the nomination.