Rush Limbaugh has proven time and again what a nasty bully he can be.Remember his feeble attempt to insult Chelsea Clinton by criticizing herappearance when she was just a child? And his racist musings on whetherblack men were equipped to play quarterback?(FYI, Rush, at least five African-Americans are starting quarterbacks inNFL right now.)

This week however, Limbaugh sank to a new low by mocking actor MichaelJ. Fox and his battle with Parkinson’s disease.

Fox has become a Limbaugh target because he has appeared inpolitical ads for Democratic senatorial candidates who support stem cellresearch, such as Rep. Ben Cardin of Maryland and Claire McCaskill inMissouri.

“He is exaggerating the effects of the disease,” Limbaugh toldlisteners Monday. “He’s moving all around and shaking and it’s purely anact…This is really shameless of Michael J. Fox. Either he didn’t takehis medication or he’s acting.”

Limbaugh ultimately offered a half-hearted apology, but it’s difficult to takethis seriously. With a weekly audience of 10 million, he lives togenerate this type of controversy. He and Ann Coulter seem to be in acompetition for who can be the most consistently repugnant and woefullyignorant.

With his acting career essentially over, Fox now works to raiseawareness of the plight of people who suffer from Parkinson’s. Even ifLimbaugh objects to stem cell research, it certainly isn’t a crime forFox to weigh in on the issue. Muhammad Ali has done this admirably. So did the late Christopher Reeve. Will they be the next to draw Limbaugh’svindictive ire?