With the midterm election just over six months away, the race for congressional control is tightening. While there is no shortage of surveys that show Democrats ahead of Republicans by as much as five percentage points, a new Harvard CAPS-HarrisX survey that isolates likely voters, not just registered voters or U.S. adults, shows a much closer race.
The survey also shows a slight edge in voter enthusiasm for Republicans and shows the GOP leading Democrats on handling the economy by six points. Looking back at past predictions, the survey tends to be within a few percentage points of election outcomes.
The Harvard-Harris survey conducted April 23-26 among 2,745 registered voters shows 50 percent of likely voters supporting a Republican and 50 percent supporting a Democrat in the midterm cycle this fall.
The survey also shows President Donald Trump’s approval rating sitting at 42 percentage points among registered voters, and 46 points among likely voters, giving conservatives an edge in the likely voter category.
The survey also shows that Republican midterm voters are more likely to say they “always” vote in midterm cycles, with 53 percent of Republicans compared to 45 percent of Democrats saying they always vote in midterm elections. Republicans also say they are “definitely” going to vote in November by three points more than Democrats, with 62 percent of Republicans and 59 percent of Democrats saying they are “definitely” going to vote in November.
Past Harvard-Harris polls leading up to major elections have been within a few percentage points of the outcome, with the polls sometimes underestimating Republican support by a few percentage points or more, making the recent polling tie a possible signal of hidden GOP strength. At least, compared to other recent surveys that show Republicans behind by five or more points.
In the Harvard-Harris poll from Oct. 14, 2024, the survey showed Kamala Harris with a two-point advantage over President Donald Trump among likely voters, with Harris earning 51 percent of the vote and Trump earning 49 percent.
With Trump beating Harris by 1.5 points in the election, the Harvard-Harris poll came close but failed to capture Trump’s win. It’s prediction of a two-point lead for Harris was flipped on election day, indicating that the survey can moderately underrepresent Republican strength.
Other surveys came closer and did not overestimate Democrats by as much. While Harvard-Harris underestimated Trump — albeit within the margin of error — the New York Times/Siena College poll from Sept. 3-6 predicted Trump beating Harris by a single percentage point.
If anything, this makes the latest Harvard-Harris survey showing a virtual tie between both parties more significant. Harvard-Harris tends to slightly underestimate conservative strength, so if the pollster is showing a tie now that tie could be obscuring a slight edge for the GOP.
The Harvard-Harris survey also slightly underestimated Republican congressional strength in the 2024 election, predicting that congressional Democrats would beat Republicans by two points. The Harvard-Harris poll from Oct. 14, 2024, found Democrats beating Republicans 51 percent to 49 percent among likely voters.
However, as we now know the GOP won more seats than expected and beat Democrats by just over 2.5 points, or 49.75 percent to 47.19 percent. Again, the Harvard-Harris survey was within the margin of error, but slightly underestimated GOP congressional strength in 2024.
While the Harvard-Harris poll has tended to overestimate Democrat strength in recent elections, it sometimes does the opposite. In the 2022 midterm cycle, as the country was recovering from covid, many pollsters including Harvard-Harris predicted a stronger showing for Republicans.
The Harvard-Harris survey from Oct. 14, 2022, showed Republicans winning 53 percent to 47 percent in November, and the actual electoral outcome was narrower, with the GOP winning by three percentage points.
In other words, the Harvard-Harris poll got the direction of the advantage correct but overestimated that advantage by several points in the 2022 midterms.
In the 2018 midterms under President Donald Trump’s first term, the Harvard-Harris poll came within a percentage point of the electoral outcome, correctly predicting a large Democrat win.
The Harvard-Harris survey from Sept. 2018 predicted congressional Democrats beating Republicans by a nine-point-margin, 45 percent to 36 percent. Democrats won by 8.6 percentage points in the election.
This establishes Harvard-Harris as a strong indicator of likely voter sentiment and shows that while it may underestimate or overestimate within the margin of error, it is generally close. It is also worth noticing how much more ahead Harvard-Harris had Democrats by in 2018 compared to now — nine points versus an equal split.
The latest Real Clear Polling average places Democrats at an advantage of 5.3 percentage points, with the Harvard-Harris poll dragging down that average compared to other recent polls. The April 24-27 survey from The Economist/YouGov shows Democrats ahead by five points. However, the Economist/YouGov survey asks U.S. adults, while the Harvard-Harris survey asks likely voters. That distinction could prove important.
What is more, Democrats have not been gaining significantly in the generic congressional ballot since January. The party has only gained 1.3 percentage points since Jan. 2, despite the Iran conflict and an increase in fuel prices putting pressure on the Republican Party.
With geopolitical issues and inflation topping the list of concerns for voters — 51 percent of voters in the Harvard-Harris poll say war and geopolitical conflict is a top concern — the midterm election could be very close. That said, the Harvard-Harris poll shows that Republicans hold a six-point advantage over Democrats on handling the economy, 53 percent to 47 percent.
While the Harvard-Harris survey may be an outlier, the survey has a strong track record among likely voters — and it has slightly underestimated Republican advantage in the past. The fact that economic issues continue to dominate, and that Republicans still hold an advantage over Democrats on those issues, indicates that if the Trump Administration is able to wrap of the war with Iran and come to a deal to reopen the Strait of Hormuz, Republicans could gain an advantage in November.
Manzanita Miller is the senior political analyst at Americans for Limited Government Foundation.
