I spotted this headline this morning and thought, “No way does he end up as the nominee.”

And now, thanks to Monmouth, we have confirmation.
Alternate headline: “CATS AND DOGS LIVING TOGETHER, MASS HYSTERIA.”

If you believe this data, Grandpa Joe has suffered a partial collapse over the last two months — even though there’s no obvious reason why. There’s been no scandal or catastrophic debate performance. What might have caused this?
Has the gaffe-o-rama caught up to him, with Dem primary voters wondering if he’s “lost a step,” to borrow a favorite euphemism? Or is this a simple matter of Dem voters paying closer attention to the race as it wears on and finding more to like in Elizabeth Warren and Bernie Sanders? It seems like there’s more to his slide here than voters just “going shopping” among candidates: Biden’s net favorable rating has tumbled 16 points since June, leaving him now less popular than Warren.
Another interesting theory floating around is that the more beatable Trump looks, the less compelling the “electability” case for Biden becomes. If Democrats start to believe that the economy is headed for a slide due to Trump’s trade war, they should be more willing to roll the dice on a candidate like Warren who excites them instead of on a blandly appealing mediocrity like Joe.
But there’s a third theory for the Monmouth results. What if … this poll is hot garbage?

Normally a reputable pollster will insist on no less than 400 respondents for a poll. Monmouth pushed this one out having sampled fewer than 300. The huge margin of error means that Biden could conceivably be polling in reality at around 25 percent, which would be lower than his polling average of 28-29 percent of late but not wildly lower. In all likelihood we just have a bum poll.
…although I can’t help noticing that the most recent national poll taken before this one found numbers similar to Monmouth’s. Last week YouGov had the race Biden 22, Sanders 19, Warren 17, another spread suggesting a de facto three-way tie at the top. Nate Silver claims that YouGov’s numbers have consistently been a bit worse for Biden than other pollsters so perhaps that’s another fluky result, but a third poll showing Grandpa falling back towards the pack would be hard to dismiss as fluky. Stay tuned.
One more data point from Monmouth, for what it’s worth. It remains an open question whether Democrats who claim to support for Medicare for All have any idea what they’re talking about. When asked if it’s “very important” to nominate someone who supports MFA, a whopping 58 percent of Dems said yes. However, when asked what sort of health-care reform they’d like to see in 2021, their answer was different:

What they’re really endorsing is a public option, not Medicare for All. In fact, even when Monmouth asked fans of the public option whether they thought the system should transform into mandatory single-payer for all *eventually*, only 18 percent said yes. A majority of Democrats overall oppose having the federal government monopolize the health insurance industry.
Here’s grampy assuring fans he’s not “going nuts.”