CBS News has jumped into the middle of the presidential race, forcing YouTube to take down a Web ad by John McCain’s campaign that the network calls “misleading” in its use of Katie Couric.

The ad, entitled “Lipstick,” accuses Barack Obama of calling McCain running mate Sarah Palin a lipstick-wearing pig. It features at the end a quote from Couric bemoaning the “continued and accepted role of sexism in American life.” Couric at the time was referring to Democratic primary coverage of Sen. Hillary Clinton.

The ad ends with a picture of Obama and a caption reading, “Ready to lead? No. Ready to smear? Yes.”

The link to the ad on YouTube now leads to a message: “This video is no longer available due to a copyright claim by CBS Interactive Inc.”

CBS News made it clear that it did not approve of the ad.