Here's the key exchange between Wolf Blitzer and Bob Woodward from Monday night.

BLITZER: In the past, when people have guessed who Deep Throat was, like Alexander Haig and John Dean, years ago, you've denied it. I noticed yesterday on "Meet the Press" when they said -- they asked you about Pat Buchanan, you sort of threw your hands up in the air with a "No comment." What's all that about?

WOODWARD: Lots of people have died, people have taken -- gone off the list because we've taken them off the list. So it's a narrowing group. And our job is to protect sources. And by further reducing the list, we tend to jeopardize disclosure of that source before he wants to be disclosed.

BLITZER: He's still alive right now, Deep Throat.

WOODWARD: Last I checked.

BLITZER: And you're still in touch with him?

WOODWARD: I'm just not going to get into that.

Like I said last night, it just doesn't sound like a persuasive explanation of Woodward's change of policy.