In 1994, after the disastrous federal raid on the Branch Davidian compound in Waco, he gave some advice to his listeners: "Now if the Bureau of Alcohol, Tobacco and Firearms comes to disarm you and they are bearing arms, resist them with arms. Go for a head shot; they're going to be wearing bulletproof vests. … Kill the sons of bitches."

He later backed off, saying he meant merely that people should defend themselves if federal agents came with guns blazing. But his amended guidance was not exactly conciliatory: Liddy also said he should have recommended shots to the groin instead of the head. If that wasn't enough to inflame any nut cases, he mentioned labeling targets "Bill" and "Hillary" when he practiced shooting.

Given Liddy's record, it's hard to see why McCain would touch him with a 10-foot pole. On the contrary, he should be returning his donations and shunning his show. Yet the senator shows no qualms about associating with Liddy -- or celebrating his service to their common cause.

How does McCain explain his howling hypocrisy on the subject? He doesn't. I made repeated inquiries to his campaign aides, which they refused to acknowledge, much less answer. On this topic, the pilot of the Straight Talk Express would rather stay parked in the garage.

That's an odd policy for someone who is so forthright about his rival's responsibility. McCain thinks Obama should apologize for associating with a criminal extremist. To which Obama might reply: After you.