Is this a signal of a Democratic rebound in the midterms, or of a successful “decoupling” from Joe Biden? Probably not, but that doesn’t mean the Politico/Morning Consult poll can be entirely discarded either. Their read on the generic ballot puts Democrats into an almost hold-serve position as up four points, 46/42.

That comes with a significant caveat, though:

Democrats hold a 4-percentage-point lead against Republicans on a generic congressional ballot, according to a new poll that comes amid low approval ratings for President Biden.

The Politico-Morning Consult poll released on Wednesday found that 46 percent of respondents would choose the Democrat when asked which candidate they would most likely vote for if the election for Congress in their district was held today, compared to 42 percent who said the Republican.

A separate 12 percent either said they had no opinion or did not know.

Let’s start with the caveats. The Politico/Morning Consult poll has been an outlier among pollsters on the generic ballot for a while. It’s part of the RCP aggregation on this polling and routinely returns results showing Democrat leads. Its previous iterations had Democrats up three, a tie, up two, and up four again in mid-May. During this entire time, both the RCP overall aggregation and FiveThirtyEight have shown the GOP up a couple of points — and that includes the Politico/MC data.

At least it’s consistent, which at least provides some longitudinal value, but why is it consistently Dem-cheery? Perhaps because 39% of its sample are Democrats, as opposed to 35% Republican and only 22% independent. It’s even arguable at the moment whether a D+4 sample provides a predictive model in this election cycle, but it’s beyond doubt that a sample with only 22% independents is hardly representative of the US electorate. Thus far we don’t have any crosstab data available from Morning Consult, but I’d bet that the indie demo doesn’t return a D+4 result.

So let’s just focus on the longitudinal value of the poll. This series has basically paralleled the RCP and FiveThirtyEight aggregations on the generic ballot most of this year, swinging between ties and D+4 for months. The last time it returned a Republican lead was in mid-February, an R+2. That makes this result a bit interesting, but all of the variation on this poll falls into its margin of error.

The same is true of the Politico/MC longitudinal results on Joe Biden’s approval ratings. Today’s poll puts it at 40/58, which is bad and consistent in terms of the gap but still a bit better nominally than the RCP aggregate from other pollsters (38.2/56.2). That again is likely because of the 39% Democrat sample Morning Consult uses, although with Biden the range of MC results is much wider than with the generic ballot. They’ve had him from 44/54 in mid-May to today’s 40/58, and a couple of 39/58s along the way too.

It’s essentially a static series in a static field, with a different range than most other pollsters. The Hill thinks this is a sign of optimism for Democrats, however:

The new polling offers a little optimism for Democrats, who are bracing for a challenging November election given rising inflation, the historical precedent that a sitting president’s party generally suffers losses in the midterms and Biden’s lagging approval ratings.

It only offers optimism if one doesn’t pay attention to the composition and history of the Morning Consult series. This is a signal that nothing’s changing for Democrats, which isn’t an optimistic sign at all.