Las Vegas ? Sen. Barack Obama said Friday that his campaign had nothing to do with a Web ad portraying his chief rival for the Democratic presidential nomination as an Orwellian figure.

Nevertheless, Obama declined to denounce the ad, which depicts New York Sen. Hillary Rodham Clinton as Big Brother. He said the ad apparently “captured the public’s imagination.”

Obama said the ad was produced by a renegade employee of a company hired by his campaign to help design his Web site. The employee, Philip de Vellis, has since left Blue State Digital, a Washington-based consulting firm, and has said he produced the ad on his own time.

The ad, posted on the online video site YouTube and viewed by more than 1 million people, depicts drones watching a Clinton speech in a trance, until a female athlete runs in, shatters the screen and breaks the monotony. It ends with the text: “On January 14th the Democratic primary will begin. And you will see why 2008 isn’t going to be like ‘1984.’” It signs off with “BarackObama.com”

“We had no idea who did it, and that’s what we said originally,” Obama told The Associated Press in a phone interview from Washington. “It turned out that he worked for a vendor of ours. But he himself said that we had no knowledge that he was doing it.”

When asked his opinion of the ad, the Illinois senator declined to denounce it, saying:

“If you scroll down YouTube there are actually probably about a hundred ads of this sort, many of them directed toward me. But I guess this just captured the public’s imagination a little more. … It’s not an ad that we would have produced in our campaign.”