On the campaign trail with Michael J. Fox by Anderson Cooper

I just got finished talking with Michael J. Fox. The actor-turned-activist is in Virginia tonight campaigning for Democratic Senate candidate Jim Webb.

Fox has drawn criticism from some who are saying he's being used to spread a misleading message. I talked about that with him a lot this afternoon, and we'll air the full interview tonight on "360."

I've never met Fox before, but he clearly is committed to the issue of embryonic stem cell research. He arrived about half an hour before the interview was to begin and took a short nap in a hotel room we'd rented.

He's been crossing the country as he campaigns for different candidates, and it has clearly taken a lot out of him. Stress makes his uncontrollable movements worse, and as you can imagine, it's been a pretty stressful couple of weeks for him.

He's not complaining, however. If anything, he seems energized by the feeling that he is making a difference.

We got a call earlier today from Rush Limbaugh's chief of staff. I thought only candidates have chiefs of staff, but apparently not. Anyway, he expressed concern that in our promo for tonight's interview we were mischaracterizing what Limbaugh said about Michael J. Fox.

In the promo, we said, "Rush Limbaugh accused him of 'faking' Parkinson's symptoms...." The chief of staff seemed to think we'd said that Limbaugh said he was faking Parkinson's. We did not say that.

Limbaugh initially said Fox was either acting or intentionally hadn't taken his medication in one of the commercials he shot for a candidate in Missouri. Limbaugh has since apologized for that, but continues to say Fox is misleading voters. (Watch Fox's ad for the Missouri candidate)

Does Michael J. Fox accept Rush Limbaugh's apology? Find out tonight at 10 p.m.