Remember when John McCain's 2000 presidential campaign was derailed by fallacious rumors that he had fathered a black child? You might think that would have caused McCain to avoid smear attacks.

Over the past few days, though, whether referencing Barack Obama's association with Bill Ayers or using Obama's middle name of "Hussein," McCain, Sarah Palin and their campaign surrogates have been steadily turning to more and more vicious personal attacks against Obama.

Thursday came yet another example of this. While on conservative comedian Dennis Miller's radio show, McCain campaign co-chairman and former Oklahoma Gov. Frank Keating brought up Obama's admitted former drug use. Calling Obama's record "very extreme," Keating went on to say that Obama "ought to admit, ‘You know, I've got to be honest with you. I was a guy of the street. I was way to the left. I used cocaine. I voted liberally, but I'm back at the center ...' But he hasn't done that."

Keating's claim that Obama has not been forthright about his drug use is absurd. The reason we know about it in the first place is because he admitted to it in his memoir "Dreams From My Father."

To his credit, Miller pointed this out to Keating, saying, "Wait, I've got to jump in, Frank. He has copped to the blow use, right? I mean, he did so in his own book; he said he did blow."

Keating replied, "Oh, yes, he did."

Reached for comment by CNN about Keating's comments, a McCain campaign aide said, "We didn’t ask him to do it. He didn’t clear it with us, but obviously he’s read Senator Obama’s books.”