Both here and in Impromptus, Jay Nordlinger has written about what he calls “self-protective denigratory preludes,” or SDPs. An example would be when someone on the Left, addressing someone else he assumes is on the Left, precedes the expression of agreement with George W. Bush by saying, “Of course I oppose nearly everything Bush stands for, but. . .” Jay suggests that everyone performs this maneuver sometimes, but that he is going to do it less.
I think Jay is being too denigratory about SDPs. Or maybe a better way of putting it is that what look like SDPs are not always intended only for self-protection. Sometimes it’s a rhetorical device designed to help persuade someone to be open to an idea to which partisan loyalty might tend to close him off. It’s a way of saying, “People on our side of the ideological divide ought to be able to see X,” where X is some observation more associated with people on the other side. The point the apparent SDPer is making, that is, may be less “I don’t want you to get the impression that I’m one of those wretched people on the other side because I think this thing” than “I want you to be comfortable thinking this thing without its threatening your sense of what side you’re on.”
There is also a non-denigratory version of the move. A self-protective affirmatory prelude (SAP?) might be, “I voted for Clinton, but I think Trump has a point when. . .” or “You know how much I love Trump, but I wish he’d stop. . .” Again, the same words could be spoken by someone wanting to avoid being deplored by whoever he is addressing, someone wanting to be more effective in convincing that person, or someone with a mix of both motives.
What all of these verbal maneuvers have in common, I think, is that they assume a social world of rigid political divides — where people are apt to dislike and dismiss ideas and figures associated with the other political tribe. So the frequency of their use is probably increasing.