I don’t have a ton to say about the idle speculation over trying to mount some kind of left-wing primary challenge to Barack Obama in 2012. I will say that one thing we’ve seen from the conservative movement over the years is that even though primaries sometimes backfire (Christine O’Donnell, anyone?) they can also be a very effective tool of ideological discipline.

But . . . you’ve got to walk before you run, and you’ve got to crawl before you walk.

How about some Senate primaries where a more progressive candidate (a) wins the primary and then (b) wins the general election? Until there’s some kind of track-record of that happening, everything else seems to me to be just idle talk.