Firebreak (n): A strip of cleared or plowed land used to stop the spread of a fire. See Also: ATF Acting Director.

Here are two things we know about the Gunwalker scandal.

A. Acting ATF Director Melson was definitely involved with Fast and Furious.

B. Obama and Holder never heard of the operation, or even of the BATFE. (Yeah, I made that last part up. But I bet they wish it were so.)

But you can be absolutely certain they don't intend the mea culpas to go any higher than Melson. During the various occupations of Afghanistan during my lifetime, I have occasionally wondered how they ever find anybody to take the job of President: It is so very ill-fated. For the past several years the same could be asked of the post of Acting ATF Director.

Big surprise! Now it looks like Melson's being offered a chance to fall on his sword:

The Justice Department is expected to oust the head of the Bureau of Alcohol, Tobacco, Firearms and Explosives, according to people familiar with the matter, amid a troubled federal antitrafficking operation that has grown into the agency's biggest scandal in nearly two decades.

Moves toward the replacement of Kenneth Melson, acting ATF director since April 2009, could begin next week, although the precise sequence of events remains to be decided, these people said.

Another one goes under the bus. I think they should add "Acting Director to the ATF table of organization. Only they should call it "Designated Scapegoat."

So will Melson go under the bus? Will he check the U-joints while he's under there? Who knows? Who cares? Doesn't matter. What matters is that he was entirely to blame. Once he's gone, the problem with ATF is all fixed. Remember that. It is very important.

White House spokesman Jay Carney, in response to questions Friday, said, "I can tell you that, as the president has already said, he did not know about or authorize this operation."

See?