Variety of factors

[PDittie]

Stating the obvious first: DU ≠ Real World.

But there are many similarities, and this thread a couple of weeks ago explained the community's preferences and trends. Excerpt:

Rounding out the top five, Bernie Sanders' level of support remains remarkably stable. Day to day, Sanders rarely loses supporters, but he only seems to pick up enough additional supporters to keep him hovering around the same percentage. Beginning the month at 7.94%, Sanders is currently perched at 7.71%. His support has never risen above 8.13% -- but has never dropped below 7.63%.

He's probably dropped a little in the last 15 days, just as Biden has, and just as Warren has risen. My thought relative to these percentages also is that as more 'undecideds' come off the fence, they move the numbers for those who aren't gaining support down a little. See: Klobuchar.

And to be Captain Obvious once again, Bernie isn't gaining any support on DU. This would also be reflected in Real World polling, too. What's worth watching is the polls under way at this moment relative to his "democratic socialism" speech, probably publishing Monday.

With two more weeks before the debates, there should be some unpredictable volatility in Real World polling numbers ... and certainly in the week after the first debate. As for DU ...