Nobody. Not me. Not the Dnc, not the DLC, not the RNC, not the Club for Growth, not the KKK, not the corpse of LBJ, not David Brooks, not J. Chait, not the Daily Kos, not the Poor Man, not Mark Kleiman, not Gillespie, not Dickey Cheney, and not anyone else knows "who the democratic candidate the repbulicans most fear" is.
All such speculation is silly. Stop granting the opponents godlike knowledge about the upcoming battle. They're as clueless as the rest of us. They don't have a preferred candidate. Stop interpreting every utterance by Drudge as evidence that Candidate X is the One They Want To Fight. It's silly.
We all have opinions, but as they say...