A new polling series involving several Senate races unveils some new interesting data patterns.
Emerson College, polling for the Hill Newspaper, conducted one of their typical survey series for key US Senate races. In this group, during the period of 8/25-28, the Emerson pollsters queried an aggregate total of 4,488 respondents in Arizona, Michigan, Nevada, Pennsylvania, and Wisconsin. Within this group, we saw serious new movement in the Wolverine and Badger States.
In Michigan, which has consistently featured a close race between Rep. Elissa Slotkin (D-Lansing) and former Rep. Mike Rogers (R), the Democrat’s lead increased to six points, 47-41%, according to the Emerson data. The bigger surprise was Wisconsin. In the Sen. Tammy Baldwin (D) – Eric Hovde (R) Emerson ballot test, the incumbent led by only one point, 49-48%.
In most of this year’s polling, the Michigan race has returned close results, and routinely followed the pattern set in the presidential contest. In 2024, this type of trend was unusual because the other competitive states consistently found the Republican candidate running substantially behind the percentages that GOP presidential nominee Donald Trump was posting.
This is not the first poll, however, that projected a separation between the two Michigan candidates. Just before Emerson went into the field with their polling series, the TIPP poll, surveying for the American Greatness organization (8/20-22; 741 MI likely general election voters; online), found Ms. Slotkin leading by 10 percentage points, or four more than the Emerson result. At the time, the TIPP poll appeared as an anomaly; instead, the benchmark may have proved the beginning of a new trend.
The one point Wisconsin spread Emerson finds between Sen. Baldwin and Mr. Hovde is much different than any other poll conducted since February with the exception of one survey taken at the end of June and the beginning of July. The data from that poll, which the Remington Research Group conducted, found the two contenders deadlocked in a 48-48% tie.
According to the Real Clear Politics data and policy site, Sen. Baldwin’s mean average lead is 6.35 percent from the 24 Wisconsin Senate polls that have been conducted this year, and the median average is seven points. Within the 24 polls, her highest margin was 12 points, reached twice, with the low being the aforementioned Remington Research tie.
It remains to be seen if the Emerson Wisconsin poll is itself an anomaly or the beginning of a new close trend.
The other Emerson results return numbers often seen in other studies. In Arizona, the Emerson data finds Rep. Ruben Gallego (D-Phoenix) leading former news anchor and 2022 Republican gubernatorial nominee Kari Lake, 49-42%. In the other four August Grand Canyon State surveys that four different polling entities conducted: Fox News, Rasmussen Reports, Noble Predictive Insights, and the New York Times/Siena College, Rep. Gallego chronologically led Ms. Lake by 15, 8, 7, and 9 percentage points.
The Emerson Nevada numbers, which show a ten point spread for incumbent Sen. Jacky Rosen (D), are consistent with the three other August Silver State polls. Here, the group of pollsters is consistent with those found in Arizona except for not including Noble Predictive Insights. In these surveys, the Rosen margin was 14, 11, and 9 percentage points.
The final state in the Emerson series is Pennsylvania. Incumbent Bob Casey, Jr. (D) is running for a fourth term. Here, Emerson finds Sen. Casey and former hedge fund CEO David McCormick (R) locked in a low single-digit battle, separated by four percentage points.
Pennsylvania has seen a greater degree of August polling than the other states. In this race, pollsters have surveyed the Keystone State electorate a total of seven times. In addition to the previously mentioned pollsters, Quinnipiac University, Franklin & Marshall, and the Cook Political Report also surveyed the Senate race.
In the early part of the month, Sen. Casey had opened a large lead over Mr. McCormick, to the tune of 13, 12, and 14 percentage points. From the polls ending August 8th to the present, the contest has tightened. Including two Emerson College polls, the margin between Sen. Casey and Mr. McCormick had lessened to 4, 3, 4, and 5 points, chronologically. This suggests a clear move in the contest and now becomes a campaign where the leader consistently posts only low single-digit advantages.
We can expect to see much more data coming from each of these states before the November 5th election. All of these contests will have an important role in determining which party controls the next Senate majority.
We offer this political insights report for your information and not as a predictor or representative of opinions of HBS or its employees.
