In midterm elections, with different candidates on the ballot in every state and district, it’s rare to see the sort of sharp, turn-on-a-dime shifts in the polls that we frequently saw during the 2016 presidential election, for example. Instead, races are more localized. But the past few weeks — during Republicans’ attempts to confirm Brett Kavanaugh to the Supreme Court — have felt more like a presidential election, where the news has largely been nationalized.

True to form, there have been some of the same sorts of arguments about the polls that I’m used to in presidential years, with competing narratives that may or may not square with the data. One plausible narrative is that the Kavanaugh hearings are helping to excite Republican voters and reduce the “enthusiasm gap” with Democrats. As The Upshot’s Nate Cohn points out, you can cobble together a credible case that polls since last Thursday’s Senate hearings have been comparatively good for Republicans. You could cite, for example, cite two new North Dakota polls showing Democratic incumbent Sen. Heidi Heitkamp down by double digits, or the several polls showing a close-ish Senate race in New Jersey, or a Quinnipiac University poll showing Democrats’ generic ballot lead down to 7 points from 14 points previously, or Upshot/Siena College polls showing GOP incumbents holding up well in districts in southwestern Ohio and coastal Virginia.

By the same measure, if you were trying to cite a series of strong Democratic polls since the hearings, you wouldn’t have much problem. You could highlight recent polls showing good numbers for West Virginia Democratic Sen. Joe Manchin, or several recent surveys that found Florida Sen. Bill Nelson having taken a small lead, or an Ipsos poll showing Democrats expanding their lead on the generic ballot since the hearings, or double-digit leads for Democrats in Upshot/Siena polls of congressional districts in Arizona and Minnesota. And there are some plausible stories behind this hypothesis, too. Kavanaugh was not a popular pick to begin with, and he has become more unpopular still in some (although not all) polls. He’s also particularly unpopular with groups such as college-educated women who typically turn out at high rates at the midterms.

The whole purpose of the various polling averages and forecasts we construct at FiveThirtyEight is to avoid this sort of cherry-picking of polls; instead, we want to evaluate all of the data in a comprehensive way. So for the rest of this article, I’m going to take a quick look at what our various metrics have said at several key points in Kavanaugh’s confirmation process, including when he was nominated in July, before and after the initial Senate hearings last month, when a Washington Post article revealed the name of Christine Blasey Ford (who accused Kavanaugh of sexually assaulting her when they were in high school) on Sept. 16, and before and after last week’s hearings with Ford and Kavanaugh.

First, here are the numbers from our generic congressional ballot polling average — and from two versions of our Trump approval rating average, one using all polls (our default version) and another using polls of registered and likely voters only.

How key metrics have changed during Kavanaugh’s confirmation process Trump net approval Date Event GOP gen. ballot margin polls of RV/LV* All polls July 8 Day before Kavanaugh nominated -7.4 -9.2 -10.8 Sept. 3 Day before initial confirmation hearings -8.8 -11.9 -14.0 Sept. 15 Day before Ford’s name disclosed -9.1 -12.6 -13.4 Sept. 26 Day before hearing on Ford allegations -8.6 -8.6 -11.4 Oct. 4 Today -8.0 -9.2 -10.7 *Registered voters and likely voters

From a 35,000-foot view, the story in the generic ballot numbers is largely one of stability. If you want to be more precise, however, the trend in the generic ballot now depends on what point in time you’re comparing against. The GOP’s current deficit on the generic ballot, 8.0 percentage points, is a bit worse than it was before Kavanaugh was nominated, when it was 7.4 percentage points. It’s slightly better than it was when Ford’s name was disclosed, however, when it was 9.1 percentage points, or since just before last week’s hearings, when it was 8.6 percentage points.

Trump’s approval ratings have largely followed the same trajectory as the generic ballot, having slumped in early-to-mid September and since rebounded slightly. It’s not clear how much of that is Kavanaugh-related, however, as the president was dealing with a lot of other news in August and early September, such as the guilty pleas of Paul Manafort and Michael Cohen. Merely staying out of the headlines while Kavanaugh was the lead story may have helped Trump’s numbers revert to the mean. It’s also not clear if Trump’s numbers have improved since last week’s Senate hearings; in the all-polls version of our average, they’ve gotten a bit better, but in the registered-voter version, they’ve gotten slightly worse. (There hasn’t yet been time for the polls to reflect any impact of Trump having mocked Ford at a rally on Tuesday night.)

We can also look at the topline numbers from the various versions of our House and Senate forecasts, which incorporate state-by-state and district-by-district polling as well as national indicators. Unfortunately, we can’t go back all the way to the date of Kavanaugh’s nomination in July because we weren’t publishing our numbers then. But we can cover the period since Kavanaugh’s initial hearings in early September. First, here’s the House:

How Republican chances in the House have changed since initial Kavanaugh hearings According to FiveThirtyEight’s 2018 House forecast Chance of GOP House Control Date Event Lite Classic Deluxe Sept. 3 Day before initial confirmation hearings 34% 22% 27% Sept. 15 Day before Ford’s name released 26 17 22 Sept. 26 Day before new confirmation hearings 22 20 23 Oct. 4 Today 29 25 28

In the Classic and Deluxe versions of our House forecast, Republicans’ numbers have reverted back to where they were in early September, with around a 25 percent chance (1 in 4) of keeping the House. However, they’re somewhat better than than they were in mid-September, when their chances had slumped to as low as 17 percent (about 1 in 6) in the Classic version of our model. They’re also a bit better than before last week’s hearings, when they were around 20 percent (1 in 5).

The Lite version of our forecast, which heavily emphasizes district-by-district polls, tells a somewhat different story. In the Lite forecast, Republicans’ House odds are a bit better than they were last week. However, they’re worse than they were a month ago, having fallen to 29 percent from 34 percent. What that means is that district-level polls have generally been getting worse for Republicans, even if national indicators have stabilized or improved slightly.

But there’s some pretty darn good news for Republicans in our Senate forecast:

How Republican chances in the Senate have changed since initial Kavanaugh hearings According to FiveThirtyEight’s 2018 Senate forecast Chance of GOP Senate Control Date Event Lite Classic Deluxe Sept. 3 Day before initial confirmation hearings 72% 68% 68% Sept. 15 Day before Ford’s name released 72 68 69 Sept. 26 Day before new confirmation hearings 69 68 69 Oct. 4 Today 76 77 77

Republicans have been favored to keep the Senate all along. But their position has improved quite a bit over the last week in all three versions of our model. In our Classic Senate forecast, for example, Republicans are now 77 percent favorites to hold the chamber, up from 68 percent before last week’s hearings.

A lot of this comes down to Heitkamp and North Dakota, where Republican Kevin Cramer is now a 2-to-1 favorite despite the traditionally strong performance of opposition-party incumbents in potential wave elections. Heitkamp’s problems might well be Kavanaugh related — she hasn’t yet been clear about how she’ll vote, but polls show a clear majority of North Dakotans favoring Kavanaugh’s confirmation. At the same time, Manchin’s numbers have held up well in West Virginia despite his having taken a similarly ambiguous stance on Kavanaugh, and some Democrats who have said they’d vote against Kavanaugh, such as Missouri’s Claire McCaskill and Indiana’s Joe Donnelly, have had decent polling numbers lately. I’m inclined toward the obvious-seeming conclusion that Kavanaugh has hurt Heitkamp, but it isn’t totally cut-and-dried.

One other thing the forecasts won’t tell you is whether changes in the topline numbers reflect shifts in voter preferences or instead changes in voter propensity to turn out. If the GOP position on the generic ballot has improved by half a point over the last week, for instance, that could be because their voters are closing the enthusiasm gap or it could be for some other reason.

But one hint comes from polls that publish both registered- and likely-voter results; the difference between these numbers is a good measure of the enthusiasm gap or turnout gap. Currently, we’re showing that likely voter polls are only about 0.4 percentage better for Republicans than registered-voter polls. That’s much smaller than the typical gap between likely- and registered-voter polls, which usually favors Republicans by anywhere from 1 to 6 percentage points in midterm years, reflecting that Democrats tend to rely on minority and young voters who don’t always turn out at the midterms. It is, however, slightly improved for Republicans from the numbers we were seeing earlier this year, when there wasn’t any gap at all on average between registered- and likely-voter polls. To complicate matters, Republicans are generally doing worse in district-level polls than you’d expect them to do in generic ballot polls, even though district polls are almost always conducted among likely voters. One possibility is that Kavanaugh is helping with Republican base turnout, but also hurting the GOP among swing voters with a high propensity to turn out, such as suburban women.

Overall, I’m inclined to conclude there’s actually something there for Republicans — that their position has genuinely improved from where it was a week ago (although, not necessarily as compared to where it was a month ago). But I’m also wary of the idea that this is necessarily a turning point, since it wouldn’t take much — a couple of good generic ballot polls for Democrats, plus a handful of good state-level results in places like North Dakota — to reverse the GOP gains in our forecast. There is truth in the idea that Republicans have had a decent week of polling, but it can also be exaggerated by cherry-picking data that’s consistent with a particular narrative.

Finally, it should go without saying that this is still a dynamic situation, and it doesn’t necessarily follow that the party that “wins” the battle over Kavanaugh will benefit electorally. The opposite could prove true. A CBS News/YouGov poll conducted earlier this week found that more voters would be angry than enthusiastic if Kavanaugh was confirmed — but also, more voters would be angry than enthusiastic if Kavanaugh was not confirmed. Whichever party doesn’t get its way on Kavanaugh will have more reason to feel aggrieved — and perhaps more motivation to turn out to vote.





FiveThirtyEight House forecast update for Oct. 5, 2018