A new Democratic primary poll is out from Monmouth University (full PDF results are here). The results for the two major candidates who have actually announced their candidacies (so, not including Biden) are:
Clinton 42% (-10%)
Sanders 20% (+4%)
In August, Clinton led Sanders 52%-16% in this poll (a lead of 36%). This month, her lead in this poll is down 14% to 42%-20% (a lead of 22%).
Bernie Sanders continues to chip away at Clinton's lead, with each passing month, as voters begin to pay more attention to the Democratic Primary race. With each additional poll that comes out, Hillary Clinton seems to look less and less "inevitable" as the Democratic nominee. Clinton's current 42% support is her lowest yet in
any poll since 2013 (when Huff Post Pollster data begins).
Monmouth's methodology has tended over the past few months to underestimate Sanders' support relative to most other polls (which is why they had him at 16% last month, and at only 20% this month, which are comparatively low numbers for him). Nonetheless, this result is in line with the trend we have seen over the past few months across all polls - Sanders continues to chip away at Clinton's lead and to gain support, while Clinton continues to bleed support. Here's the updated overall national polling trend, courtesy of Huff Post Pollster:
And here are the results for candidates who either have not announced that they are actually in fact running or who have negligible support:
Biden 22% (+10%)
O'Malley 1% (-1%)
Webb 1% (-1%)
Chafee 0% (no change)
The most relevant of these is obviously Biden. Recently, of course, there has been an uptick in speculation that Joe Biden might run for President (without any actual indication that he in fact will do so).
What is interesting about the recently flurry of Biden media buzz is its effect on Clinton as compared to its effect on Sanders. The Biden boomlet has taken support entirely away from Clinton, while Sanders has not only maintained his existing support, but has continued to rise.
It seems that the most likely explanation of this is that low information voters who had been saying that they supported Clinton have been abandoning her in droves, and flocking to Biden, who pollsters continue to include in their polls even though he has not said that he is actually running.
One question one might ask is why many of those voters are now saying they support Biden, rather than Sanders. If one looks a bit deeper into the poll, the primary answer is fairly obvious - name recognition. As the sitting Vice President, basically everyone has heard of Joe Biden. Only 21% of voters do not know enough about Biden to report a favorable/unfavorable opinion. By comparison, Sanders 45% of voters still don't know enough about Sanders to report a favorable/unfavorable opinion of Sanders. Across time, as Sanders has gotten his message out to more people, and as that "no opinion" number has dropped, Sanders' support has picked up in tandem.
One other note - we probably shouldn't take the unfavorables for any of the candidates too seriously here. All candidates (even O'Malley, Chafee, and Webb) have about the same 10-20% unfavorables. It seems that there is a group of about 10% or so of poll respondents that say they have an unfavorable view of everyone, probably regardless of whether they have even heard of them.
So while a lot of the media reporting for this poll will probably be all about Biden, if you look a little bit more closely, you can see that in fact this poll is just one more piece of the continually growing pile of polling evidence supporting the upward trend in Bernie Sanders' support and the downward trend in Clinton's support, as the Clinton/Sanders race continues to become more and more competitive nationally.
11:27 AM PT: An additional comment ---
Some Clinton supporters are arguing that the real story here should be "Sanders drops to 3rd behind Biden." They are also arguing that it is especially bad that Sanders is slightly behind Biden, given that Biden is not even a candidate. Do they have a point?
I would say, to some extent, yes. But overall, not really. Here's why.
There are lots of people who are not candidates, who, if they were included in a poll, and if they were treated as candidates, would no doubt be ahead of Bernie Sanders, and many of whom would also be ahead of Clinton. If Barack Obama were included in this poll, I am very confident that he would be beating both Hillary Clinton and Bernie Sanders. If Michelle Obama were included, I think the same is likewise true. But that's not relevant, because neither of them are candidates (and in the case of Barack, he is not even eligible!). The same thing would be generally true of lots of people who are generally popular and are not politicians. Angelina Jolie, Alan Greenspan, Pope Francis, Queen Elizabeth, Sonia Sotamayor, Santa Claus, Jesus.
That's all very interesting, but not very relevant. It's just a reflection of the fact that people are fed up with politics as usual, and with politicians. But it's not really all that relevant unless and until someone actually becomes a candidate.
To a significant extent, the reason why Biden is doing relatively well is precisely because he is not a candidate. If he does enter the race, he will quickly become just another candidate, will face more media scrutiny, and the luster that he is currently basking in will start to fade off a bit.