It has been axiomatic, in American politics, that it’s hard to beat a southern conservative Democrat. It can be done, of course, but the combination — in recent years, anyway — of moderate conservative populism and Democratic party muscle has been pretty formidable. Southern Democrats were in many ways analogous to western Republicans: a powerful political profile.

As the Democratic party has moved farther and farther to the left, this became less true. Bill Clinton is often overheard to lament his party’s move to the anti-business left. Hillary Clinton, if she runs and if she has any credible primary challengers will have them, probably, from the left side of her party.