Limbaugh: Michael J. Fox Exploited Disease

His body visibly wracked by tremors, actor Michael J. Fox appears in a political ad that was the subject of widespread discussion on Monday after conservative radio commentator Rush Limbaugh claimed Fox was "either off his medication or acting."

A victim of Parkinson's disease, Fox speaks out in the ad for Missouri Democratic Senate candidate Claire McCaskill, who supports embryonic stem cell research.

"I think this is exploitative in a way that's unbecoming of either Claire McCaskill or Michael J. Fox," Limbaugh said on his syndicated show.

On his Web site Tuesday, Limbaugh appeared to back away from his accusation.

"All I'm saying is I've nev...