re: What you are suggesting is that the Democrats let Ralph Nader (or some other far left idiot) take over the extreem left...
To do so, would in the short term, cause the Democrats to lose a general election in a big way, and the Democrats know it.
The question is, would the Democrats be willing to drive the far left out of the party even if it means risking a huge loss in a national election?
Answer: No. Even if it was for the good of the party (longer term) they couldn't bring themselves to do it. They want to win now. Not next election...
For that reason, they are going further left, and they will continue to do so until they are completely in the moonbat zone.
Scott Evil