What polls do and don’t tell us about the 2026 midterms

Can the polls be trusted? It depends on what you’re trusting them to do.

Even the most carefully conducted polls are imprecise snapshots of public opinion, not precision instruments — and when they’re pressed into predictive tools, they don’t always get it right. But while surveys can’t provide an unambiguous answer on who’s ahead in tight races, they often do paint a clear and important picture of the political landscape.

The contours of some findings are sharply drawn enough to be visible even through the shadows of potential polling error. Poll after poll has found President Donald Trump’s approval rating in the mid-to-low-30s nationally. Surveys also show a broad consensus that Americans, shaken by cost of living concerns , largely take a dim view of the economy and Trump’s stewardship of it; that there’s little enthusiasm in any corner about the current state of the nation; and that voters are overwhelmingly looking for change — even if they may not all agree on precisely what that change should look like.

Similarly, Democrats’ lead on the national “ generic ballot ” has been consistent and robust enough to suggest that the party has an overall advantage — and it would require an unprecedented level of polling error to overcome that. But there’s far less certainty about the precise level of that advantage, or how that might play out in individual races. Even a small difference in Democratic strength compared to what the polls suggest could mean the difference between a blue wave that sweeps well into Republican territory, and one that fails to overcome a deeply Republican-friendly Senate map.

One thing that’s challenging for pollsters this year is that there’s another finding that looks simultaneously like a defining factor of the race and a potential source of polling error: the yawning gap in partisan enthusiasm about voting.

Polls — consistent with early voting data — have found that, compared to Republicans, Democrats report being far more motivated to vote this year. That’s playing a role both in pollsters’ efforts to get people to answer surveys, and in their attempts to identify which potential voters will actually end up casting ballots in this election.

Per Gallup , the Democratic enthusiasm advantage in any midterm dating back to 1994. That’s in part because, particularly in his second term, Trump provokes far more fervent opposition than he does ardent support. It also owes in part to the growing education divide in American politics, with college-educated voters likelier than those without degrees both to turn out in a midterm year, and to vote Democratic if they do.

What early voting data is showing ahead of the 2026 midterms

But that same enthusiasm divide could also be shaping voters’ willingness to respond to polls.

In a Washington Post-Schar School poll of Kansas, for instance, registered Democrats who were contacted by interviewers were far likelier than registered Republicans to complete the survey. While that disparity hasn’t been universal this cycle, the final set of New York Times/Siena College polls also saw a similar response pattern.

This type of variation, sometimes called “differential nonresponse,” isn’t an entirely new challenge for pollsters. Some types of people have always been more likely than others to answer surveys, including older adults, those with higher levels of education and those who are more civically engaged. Pollsters address that disparity by weighting their results to make the demographics of their sample look more like the broad universe of people they’re trying to measure. Increasingly, that also includes weighting to known partisan targets, such as the levels of party registration in a state or vote choice in the 2024 election.

What concerns pollsters are those patterns that aren’t fully corrected for, even after weighting to demographic and partisan targets. A poll could have the “right” number of Republicans and Democrats to reflect the electorate but not reach the right mix of voters within each party.

Not every registered voter turns out to cast a ballot in each election — in most years, 40% or more sit it out — and that can also complicate the picture for pollsters. In order to reflect the views of those who do ultimately turn out, pollsters identify likely voters, and those efforts can be complicated by the same factors that make it hard to reach less enthused potential voters.

There’s a possibility that some types of Republicans may be too disengaged to respond to surveys, but still sufficiently motivated that they’ll end up voting — or that the most engaged and enthusiastic Democrats will be overrepresented in surveys.

Even if the polls accurately reflect the dynamics at the time they were conducted, there’s still room for a shift after that polling is completed if Republican voters coalesce late around their candidates.

CNN’s final state polls , for instance, gave voters an option to say they wouldn’t support either candidate in the upcoming Senate race — and even after being asked a follow-up question about which way they’d lean, 6% to 8% in each poll said that, between the two leading candidates, they’d back “neither” or someone else. The poll also pressed voters to choose which party they’d rather see in control of the Senate, even if they initially said it didn’t matter to them. Looking at those two questions together tells us that in most of these polls, voters who favor GOP control were more likely than those who’d rather see a Democratic win to opt out of picking a major-party candidate — by about 9 points in Texas, 6 points in Kansas and 4 points in Michigan.

That could well reflect what happens on Election Day. The Republican nominees in Texas and Kansas, Ken Paxton and Roger Marshall, face specific image problems that have made it more difficult for them to consolidate their party’s support, and it’s fully plausible that GOP-inclined voters in those states might end up taking a pass on the race altogether. But it also suggests that Democrats haven’t yet sealed the deal . In a set of relatively tight races, that could be enough to significantly tighten margins or change the outcome of some races altogether.

On the other hand, it’s not a given that any polling miss would be in favor of the Democrats. Presidential polls in the past three cycles have underestimated Republicans’ share of the vote relative to Democrats : by around 3 points in 2016 and 2024, and close to 5 points in 2020.

But there hasn’t been a similar pattern in Trump-era midterm elections . Nor is it guaranteed that polling misses would look the same across the many different states in play.

As we wrote in 2024 , polling data is a single, imperfect gauge of people’s opinions. But polls of the US, ultimately, are a means of talking to Americans across a wide range of demographics, life experiences and views, on topics that stretch far beyond elections, or even politics. In a deeply fragmented society, and with social media often reflecting an unrepresentative sample of the loudest voices, they’re still a valuable tool for understanding the country as a whole.

民调可信吗？这取决于你希望它们做什么。

即使是最精心设计的民意调查也只是对公众舆论的粗略反映，而非精确的预测工具——当它们被用作预测工具时，也并非总能准确无误。虽然民调无法就势均力敌的选情给出明确的胜负判断，但它们通常能够清晰而重要地描绘出当前的政治格局。

一些调查结果的轮廓清晰可见，即使考虑到民调可能存在的误差。一项又一项的民调显示，唐纳德·特朗普总统在全国的支持率徘徊在30%左右。调查还显示，民众普遍认为，受生活成本上涨的困扰，美国民众对经济状况和特朗普的执政能力普遍持悲观态度；民众对国家现状普遍缺乏热情；选民们强烈渴望变革——即便他们对变革的具体形式可能存在分歧。

同样，民主党在全国“普选”中的领先优势一直稳定且稳固，足以表明该党拥有整体优势——需要前所未有的民调误差才能扭转这一局面。但这种优势的具体程度，以及它将如何在具体选举中体现，却远没有那么确定。即使民主党的实际实力与民调结果存在微小的差异，也可能导致截然不同的结果：要么是席卷共和党传统票仓的蓝色浪潮，要么是无法撼动共和党在参议院的绝对优势。

今年民调机构面临的一个挑战是，还有另一个发现，它既像是决定选情的关键因素，又像是民调误差的潜在来源：那就是两党对投票的热情存在巨大差距。

民调结果与提前投票数据一致，显示与共和党人相比，民主党人今年的投票积极性更高。这既影响了民调机构吸引民众参与调查的努力，也影响了他们确定哪些潜在选民最终会投票的尝试。

根据盖洛普的调查，自1994年以来，民主党在历届中期选举中都占据优势。部分原因是，尤其是在特朗普的第二个任期内，他引发的强烈反对远超热情支持。此外，美国政治中日益扩大的教育差距也起到了一定的作用：受过大学教育的选民比未受过大学教育的选民更有可能在中期选举中投票，而且如果投票，他们也更有可能投给民主党。

2026年中期选举前的提前投票数据显示了什么？

但同样的热情差异也可能影响选民对民意调查的回应意愿。

例如，在《华盛顿邮报》和沙尔学院联合进行的堪萨斯州民调中，接受访员采访的已登记民主党人比已登记共和党人更有可能完成调查。虽然这种差异在本轮选举周期中并非普遍存在，但《纽约时报》和锡耶纳学院联合进行的最后一轮民调也显示出类似的响应模式。

这种差异，有时被称为“差异性无应答”，对民调机构来说并非全新的挑战。某些人群的回复率历来高于其他人，例如老年人、受教育程度较高者以及公民参与度较高的人。民调机构通过对结果进行加权来解决这种差异，使样本的人口统计特征更接近他们试图衡量的广大群体。此外，这种加权也越来越多地包括根据已知的党派目标进行加权，例如某个州的政党登记率或2024年大选的投票选择。

民调机构担心的是，即使根据人口统计和党派目标进行加权，某些模式仍然无法得到完全修正。一项民调可能拥有足够数量的共和党人和民主党人来反映选民构成，但却无法涵盖每个党派内部所有选民的正确组合。

并非所有登记选民都会在每次选举中投票——大多数年份，有40%甚至更多的人选择弃权——这也会使民调机构的工作变得复杂。为了反映最终投票者的观点，民调机构会识别出可能投票的选民，但这些工作也会受到与接触那些投票热情不高的潜在选民相同的因素的影响。

有可能某些类型的共和党人对政治漠不关心，不愿参与调查，但他们仍然有足够的动力去投票——或者最积极、最热情的民主党人在调查中的比例可能会过高。

即使民调准确反映了当时的形势，但如果共和党选民在后期团结在候选人周围，民调结束后仍有可能发生变化。

例如，CNN的最终州民调允许选民选择是否支持即将到来的参议院选举中的任何一位候选人——即使在被追问倾向于哪一方之后，每项民调中仍有6%到8%的受访者表示，在两位领先的候选人之间，他们“都不支持”或支持其他人。该民调还要求选民选择他们更希望哪个党派控制参议院，即使他们最初表示这无关紧要。综合这两个问题来看，在大多数民调中，支持共和党控制参议院的选民比希望民主党获胜的选民更有可能选择不选择主要政党的候选人——在德克萨斯州高出约9个百分点，在堪萨斯州高出约6个百分点，在密歇根州高出约4个百分点。

这很可能预示着选举日的走向。德克萨斯州和堪萨斯州的共和党候选人肯·帕克斯顿和罗杰·马歇尔都面临着特定的形象问题，这使得他们更难巩固党内支持，因此，这些州倾向于共和党的选民最终完全放弃投票的可能性很大。但这同时也表明，民主党尚未锁定胜局。在一些选情相对胶着的选区，这足以显著缩小差距，甚至彻底改变某些选区的最终结果。

另一方面，民调结果出现偏差并不一定意味着对民主党有利。过去三届总统选举的民调都低估了共和党相对于民主党的得票率：2016年和2024年低估了约3个百分点，2020年低估了近5个百分点。

但在特朗普时代的中期选举中，并没有出现类似的模式。而且，民调结果与实际结果的偏差在众多不同的摇摆州也未必会完全相同。

正如我们在2024年所写，民调数据只是衡量民众意见的一个单一且不完美的指标。但归根结底，美国民调是与不同人口统计特征、生活经历和观点的美国人对话的一种方式，其话题远不止于选举甚至政治。在一个高度分裂的社会中，社交媒体往往反映的是少数声音，而非具有代表性的声音，民调仍然是了解整个国家的重要工具。