If this has not become a Cain campaign talking point by the time you read this, count on his staff to trot it out soon as a sign of the candidate’s excellent sense of humor.

       Seriously, folks: The Cain campaign is slowly disappearing into the sunset.  His Libya moment is disqualifying. The sexual harassment charges are hurting him among Republican women. And perhaps the most devastating mistake he made was to signal during that Milwaukee Journal-Sentinel interview what could be seen as a bit of sympathy for public-employee unions. As the paper reported:

Cain was asked whether he thinks public employees should be able to collectively bargain.

“Yes,” he said, “but not collective hijacking. What I mean by that, if they have gotten so much for so many years and it's going to bankrupt the state, I don't think that's good. It appears that in some instances, they really don't care.”

. . . Asked about last week's vote in Ohio, in which the state's new collective bargaining law was rejected by voters, Cain said that “maybe they tried to get too much and as a result it failed.”

National Review’s “The Corner,” essential online reading for conservatives, summarized Cain’s comments with this headline: “Cain Supports Collective Bargaining for Public Employees.” That headline will damage Cain among conservatives more than anything written about his Libya meltdown. Among Republican primary voters these days, you can survive sexual harassment charges for a while, and you might even be forgiven some gaffes. But you can’t give an inch to unions.  The only question now is how quickly Cain descends into single digits.