I think he will if he have to. He's been able to avoid getting dirty so far because he's realized he can talk straight to the U.S. and we'll still accept him. It helps that it elevates the discourse, but he's a man trying to get elected, just like any other. He's not any better than anyone else, aside from being the best candidate.

ExceptforPaulKucinichandGravel

The guy is gunna have to if he wants to stay in the race.

I doubt he will begin mud slinging because it would be very poor strategy. He's built a lot of his campaign on his integrity and his unwillingness to play dirty; It would be downright idiotic to throw this approach away now that people like him for this very approach. I'm not too worried: He'll keep it clean.

Why ruin his reputation now?

I think he will continue on the high moral ground to the end. What a pity =)