WASHINGTON - Weeks after radio personality Rush Limbaugh began airing a parody titled "Barack the Magic Negro," the song about African American Sen. Barack Obama's popularity with many white voters is drawing fire from critics who say it is racist.

The audio clip features a singing comedian imitating the Rev. Al Sharpton, bemoaning Obama's popularity with whites who will, the lyrics predict, "vote for him and not for me 'cause he's not from da hood."

Limbaugh's critics say the song goes too far, particularly because the piece is spreading on the Internet at a time when Obama faces heightened security concerns fueled in part by hateful remarks and threats.

"We take these things seriously because there's a consistent pattern of them making their way into the mainstream media and then the mainstream consciousness," said Karl Frisch, a spokesman for Media Matters, a nonprofit media watchdog group that has been monitoring the broadcasts. "It's important to shoot these things down."

Obama, meanwhile, has been the subject of explicit, angry, often racist comments not only in e-mail and letters but in Web postings. Samples of those writings were reviewed by members of Congress last week when they recommended that the Illinois Democrat be given protection by a Secret Service detail.

As for Limbaugh and the song, it started in March, shortly after the Los Angeles Times published a provocative column by a black writer calling Obama the "Magic Negro." The article said Obama fits the prototype of the black cinematic figure who arises to "assuage white guilt over the role of slavery and racial segregation in American history."

Not long after that column was published, Limbaugh began to air his Barack song, sung to the tune of Puff, the Magic Dragon."

Aides to Obama said they were not bothered by the parody, a slide-show version of which is available on YouTube.

"It's not the first dumb thing said during the course of this campaign and it likely won't be the last," Obama spokesman Bill Burton said.