Over at TNR, Christopher Orr makes some valid points on the risk McCain runs in bringing up Ayers tonight. (Orr also wonders why McCain would telegraph his decision to raise Ayers, as I did yesterday.)

Writes Orr:

It's not hard to envision how this may play out: McCain will raise Ayers in that awkward, semi-comic manner of his, as if he's not really sure it's something he wants to be bringing up. (Possibly moderator Bob Shieffer will bring it up for him, which would help, but I suspect any comment he makes will still sound uncomfortable.) The real-time viewer response needles will nosedive, as they have almost every time McCain has attacked in the debates so far.

Obama will very reasonably respond that it's a distant association, that he was 8 years old when Ayers committed his crimes, that he deplores said crimes, etc., etc. Then he'll turn it around on McCain, pointing out that it is all very old news, and the McCain campaign didn't think it was worth discussing until it found itself in a deep electoral hole.

If McCain's Ayers card plays out the way Orr describes it, yes, that's probably what would happen. But that's not the only way. So what McCain would have to do is mention Ayers in a way that would make Obama's stock response sound ridiculous.

In an interview with Obama strategist Robert Gibbs last week, Mark Halperin showed how this could be done. Watch the video. Essentially, what Gibbs can't answer is whether it's appropriate to have professional ties to someone who's committed terrorist acts.

How McCain can get to that question is by tying Ayers to Obama's judgment, not, as Orr writes, in a generic "semi-comic manner." Point is, if McCain is going to mention Ayers he has to tie him to something larger so that it's not a non sequitur -- and thereby make Obama's rejoinder sound contrived and beside the point.