New York, Jan 15: US presidential hopeful Barack Obama’s so-called ‘clean campaign’ turned slightly mucky when one of his staffers took a swipe at rival Hillary Clinton through the candidate's theme song.

As Obama and his wife Michelle walked proudly into his victory party following his surprising win over Hillary in the Iowa caucuses, the sound system blared rapper Jay-Z’s song “99 Problems.”

The song contains the lyrics: "I got 99 problems, but a bitch ain't one."

Some shocked listeners at the Clinton camp took it as a not-so-cunning reference to Hillary.

"We didn't know he used that," the New York Post quoted a Clinton spokesperson, as saying.

Obama has openly admitted his love for rap songs.

"I tell you what, I can tell you the kinds of stuff I love dancing to . . . I'm sort of the generation of Stevie Wonder and Earth, Wind and Fire," he told CNN on the campaign trail.

Clinton, who seems less loyal to any musical style, entered her New Hampshire victory party to "Ain't No Mountain High Enough," by Marvin Gaye and Tammi Terrell.

However, now she's using the Big Head Todd and the Monsters rock song "Blue Sky."

"We use a variety of songs. Those are the most recent," said Clinton's spokesperson. (ANI)