There will likely be a lot of complaining about last night's debate brawl, but in fact it was both a relatively entertaining and substantive debate (though the media could do more to truth-squad and not be mere passive observers).

More importantly, every candidate did what they needed to do.

Clinton had to keep the pressure on Obama in hopes of keeping him down. Obama had to stand up for himself, and use the inaccurate attacks against him to make the case he could better forge a working majority. Edwards needed to try to exploit Clinton-Obama squabbling and rise above the fray.

Some might say Clinton was shrill in her attacks, but the same was said in New Hampshire, and proved irrelevant. Some might say Obama lost his cool, but as with Clinton before sometimes you need to show a little fire when your credibility is on the line.

Yet Obama is still the one with the most work to do.

He stopped some bleeding by playing defense and debunking the Clinton attacks. Now, he needs to go on offense, and refocus the overall debate on his terms.

Towards the end of the debate, he made a move along the lines suggested here earlier, reframing the entire "Ready on Day One" discussion:

What I want to really focus on is this issue of national security, because I think you've [Clinton] repeated this a number of times. You are the person best prepared on national security issues on day one, and so if you're running against John McCain, that you can go toe-to-toe.

I fundamentally disagree with that. And I want to tell you why, because I believe that the way we are going to take on somebody like a John McCain on national security is not that we're sort of ... like John McCain, but not completely. You know, we voted for the war, but we had reservations.

I think it's going to be somebody who can serve a strong contrast and say, "We've got to overcome the politics of fear in this country."

As commander-in-chief, all of us would have a responsibility to keep the American people safe. That's our first responsibility. And I would not hesitate to strike against anybody who would do Americans or American interests' harm.

But what I do believe ... is that we have to describe a new foreign policy that says, for example, I will meet not just with our friends, but with our enemies. Because I remember what John F. Kennedy said: that we should never negotiate out of fear, but we should never fear to negotiate.

Having that kind of posture is the way I think we effectively debate the Republicans on this issue. Because if we just play into the same fear-mongering that they have been engaged in since 9/11, then we are playing on their battlefield.

But, more importantly, we are not doing what's right in order to rebuild our alliances, repair our relationships around the world, and actually make us more safe in the long term.

That is not as pointed as what I laid out earlier. We'll have to wait and see if he chooses to sharpen that argument, or if he chooses another area with which to make a sharp contrast.

Or if he stays in the place where he's been most comfortable -- arguing he is most able to win big in November and forge a working majority to enact the change all the Dem candidates support.

But as that challenges Clinton indirectly and not directly, it's a tricky one to rely on while facing a barrage of attacks.