In the last few weeks, pundits have been egging on Barack Obama and John Edwards to get tougher on Hillary Clinton, and they did. But it’s a fine line and shifting between the good earth and the mud puddle and the danger of stepping into it is always that you get some on yourself — and say something about yourself. Did the boys go too far? That’s the way Bill Clinton presented them lately, defending his wife. And that’s the way Hillary Clinton painted them last night at the CNN Democratic debate when she came out attacking the attack.

It was a well-staged sound bite: “I don’t mind taking hits on my record, on the issues, but when somebody starts throwing mud, at least we can hope that it’s accurate and not right out of the Republican playbook.”

Note the body language on this clip. At the very beginning, Joe Biden is shaking his head and smirking like the boy on the edge of the dance floor who can’t get a dance but is acting like he doesn’t care. After Clinton slaps back, look at John Edwards’ narrowed eyes; you can see his wheels spinning, wondering how to get out of this: how to attack the attack on the attack. Right there in that few seconds, you see the vicious cycle of negative campaigning. And the way out of it is always taking the high ground:

Sound bite: “But for him to be throwing this mud and making these charges, I think really detract from what we’re trying to do here tonight. We need to put forth a positive agenda for America.”

Cue cheer from a pro-Hillary crowd in the auditorium. Give Clinton the point in this mud-wrestling match.

And here’s Clinton going after Obama’s attacks on health care, “setting the record straight.” In the debate, it was quite a little boxing match but on YouTube, Clinton gets to put up just her sound bite scolding him. Give YouTube a point in the candidates’ books.

And finally, here’s Clinton answering the charge that she’s playing the gender card coming back with a rousing run on the high ground about the diversity of the Democratic field:

Sound bite: “I understand very well that people are not attacking me because I’m a woman. People are attacking me because I’m ahead. As Harry Truman famously said, ‘if you can’t stand the heat get out of the kitchen.’ And I feel very comfortable in the kitchen.”

Meanwhile, over in Edwards’ corner of YouTube, he picks a clip that has him sweating a bit as he has to spend time defending his attack with phrases like “that’s not what I’m saying.” He’s not so much taking the high ground as retreating.

Sound bite: “You know, before I came over here tonight, I was thinking, we’re going to have this debate and when we finish all of you are going to be on television saying, oh who scored points, who won the debate. All of us are going to be fine. The question is, will America be fine? … There’s nothing personal about this. This is about what America needs to be.”"

And now here’s Obama retreating from his attack mode when he’s asked why he said he didn’t believe Clinton was able to unite the country:

Sound bite: “That’s not what I said, what I said was I thought I could do it better, that’s why I’m running for President. If I didn’t think I could do it better, then I wouldn’t be running for President.”

There’s a classic in circular rhetoric.