Obama can lead Republicans around by the nose, so he can certainly get red-state Dems to fall in line.
I think you are right but it probably has more to do with how stupid Republicans are.
The Dem leadership can coerce whatever they want from the people. They know where all of the skeletons are hidden just as they do with the -R’s. When Harry and thge “Queen bitch of the House” proclaim something done, IT GETS DONE”.