Well, no — for a few reasons beyond the caveats that apply to that Ohio result. Most important is that, while special-election shifts correlate reasonably well with the margins in the national House vote during election years, there is no similar correlation at the presidential level.
We can assess this using the special election result data compiled by DailyKos and, specifically, the site’s Special Elections Index (SEI) — a comparison of special election results not only to the most recent presidential race but also to other recent elections in the district. The idea is to measure shifts in a race while reducing the effects of particularly dramatic election cycles. A lot of results, for example, might look relatively Republican if compared with Barack Obama’s success in the 2008 election.
What DailyKos has found is that their index correlates well with those House margins. You can see that below. The diagonal, dashed line represents a perfect match between the SEI and the national House margin — that is, the SEI was exactly the same as the margin. So years that appear close to the line had a closer relationship between those metrics.
And, with a few exceptions, most years are pretty close to that line.
One that isn’t particularly close, incidentally, is 2022. It’s one of two elections in which the SEI favored Democrats while the House results favored Republicans.
The question of why that gap exists is a fundamental one. It seems likely that it’s a function of the difference in turnout: While midterm elections don’t see the level of turnout that presidential ones do, they do generally pull more people to the polls than special elections. In recent years, special elections have been influenced in part by heavy turnout from Democrats angry about Roe v. Wade being overturned; in November 2022, though, that anger was to some extent subsumed into a larger mix of voters.
That question lingers for November: To what extent will the energy Democrats have enjoyed in special elections carry over into a presidential contest with more voters? That’s a corollary to another difficult-to-answer question: How will 2024 turnout compare to the record voting levels seen in 2020? Could lower turnout from uninterested voters offer more of an advantage for candidates supported by the most motivated voters? (Some early indications suggest that it might.)
But we probably shouldn’t assume that the SEI value — still undetermined for 2024 but advantaging Democrats — will tell us about the presidential popular-vote margin. Since 1992, there’s been much less of a correlation between presidential results and the SEI than for House results.
Part of this is driven by 1996, which was an outlier. Republicans fared well in special elections, but President Bill Clinton won reelection easily. Take that year out and the correlation is a little stronger — but still not as strong as the House results. That may be in part because there are fewer comparable elections, but it’s not only that. And adding more elections might just as easily loosen the correlation, of course. No reason there wouldn’t be another 1996.
The simplest assumption here is the least satisfying one: We simply don’t know if the results in special elections will tell us much about November. It is, as we’ve noted often before, an unusual election occurring under unusual circumstances. Perhaps this is why SEI doesn’t correlate as well to presidential races, political events unto themselves.
There is one useful note of caution for those who view special election results as a reason for optimism about Biden’s reelection chances. We have an example of how those elections compare to national results under conditions like those at the moment. That’s the results from 2022, in which the special election results overstated how Democrats might fare nationally.
