How large are their concerns? Within 72 hours of Biden winning his first state in the nomination fight -- a larger-than-expected victory in South Carolina -- the entire field of pragmatic/moderate/establishment types have left the race, with the exception of free-spending billionaire Mike Bloomberg.

And you can bet that if Bloomberg doesn't wind up with more delegates than Biden after tomorrow, the former New York City mayor will come under huge pressure to put his ego aside and get behind Biden too.

Still, it's not at all clear to me that the Democratic establishment can actually stop Sanders. The Vermont senator looks headed for victories in California and, to a lesser extent, Texas on Tuesday. And there's virtually no scenario I can imagine where Sanders doesn't end Super Tuesday with a clear delegate lead over Biden and everyone else.

The actual goal for the establishment may well to simply keep Sanders away from the 1,991 pledged delegates number that would formally make him the party's nominee.

Even if successful, of course, that effort would likely require superdelegates to decide the nomination -- in Biden's favor -- on a second ballot. Which, well, could be problematic.

The Point: The Stop Sanders movement is now in the light of day. But is it too late?