Nathaniel Rakich argues that “Republicans Are Just A Normal Polling Error Away From A Landslide — Or Wiping Out” at FiveThirtyEight:
With just five days until Election Day, Republicans are in good shape in the FiveThirtyEight forecast. If each party were to win every race they are currently favored to win, Republicans would have 51 Senate seats and Democrats would have 49, according to our Deluxe forecast as of Wednesday at 3 p.m. Eastern.1 And if the same thing happened in the House, Republicans would win 225 seats and Democrats would win 210.
But those gains would be modest by the standards of midterm elections. In other words, according to the FiveThirtyEight forecast, this likely won’t be a “red-wave” election like 2010 (when Republicans picked up 63 House seats) or 2014 (when Republicans picked up nine Senate seats). Instead, it’s looking like more of a “red ripple.” But that doesn’t mean a red wave is impossible.
Our forecast emphasizes probabilities, not binary outcomes: Democrats and Republicans are only slightly favored to win many of those seats, and a seat with a 60-in-100 chance of going blue votes Republican 40 out of 100 times. As readers of FiveThirtyEight are undoubtedly aware, it’s not unusual for polls to be a few percentage points off the final mark (this is normal and just a reality of our uncertain world). Since 1998, polls of U.S. Senate elections conducted within three weeks of Election Day have had a weighted-average error of 5.4 percentage points, and polls of U.S. House elections have had a weighted-average error of 6.3 points.2
…it’s also possible that pollsters have fixed the problems that plagued them in 2016 and 2020 — maybe even overcorrected for them — and that the current polls are too good for the GOP. In other words, a wide range of scenarios is possible in this election: everything from a Republican landslide to a world where Democrats hold the House and gain seats in the Senate.
Rakich gets down to cases with charts for key Senate and House races, then concludes:
To emphasize again, these are all hypothetical scenarios. If there is a pro-Republican or pro-Democratic polling error, it will almost surely unfold differently. Hopefully, though, this thought exercise has recalibrated your expectations. Of course, the polls could also be extremely accurate — as they were in the 2018 midterm. But you should be mentally prepared for something resembling the above scenarios too.
With so many close margins showing up in the better polls, prepare for surprises. Perhaps the biggest question mark is, who will control the U.S. Senate when the dust settles. As for the role of polling errors, it’s not likely that all or even most of the polls are going to make the same mistake, one way or the other. And keep in mind that it’s “midterms,” plural, not singular.