The prospect of a Democratic “blue wave” in the US midterm elections may be less certain than some polls suggest, with experts warning that Donald Trump’s supporters could be under-represented in surveys.
Democrats currently hold an advantage over Republicans in several polls ahead of the 3 November elections. However, some pollsters have questioned whether that lead is being overstated because Republican voters are less likely to respond to surveys, according to a report by Axios.
Polls underestimated Trump’s support in the 2016, 2020 and 2024 presidential elections. Although surveys have generally been more accurate in midterm elections, some also underestimated Republican support in 2022, Scott Keeter, a senior survey adviser at the Pew Research Center, told Axios.
The RealClearPolling average of the generic congressional vote currently puts Democrats about eight percentage points ahead of Republicans.
The Cook Political Report forecasts that Democrats could gain between nine and 19 seats in the House of Representatives, potentially giving them a narrow majority. In the Senate, it projects a net Democratic gain of two to six seats. The party would need to gain four seats to take control of the chamber.
However, researchers say Republicans have become less likely than Democrats to participate in telephone surveys. Pollsters have responded by giving greater weight to Republican respondents, but this approach may not fully account for those who do not answer.
“The adjustment assumes that Republicans who respond to a poll are similar to the Republicans who don’t respond to the poll,” Matthew Tyler, an assistant professor of political science at Rice University, told Axios.
Tyler warned that the assumption could distort the results. Republicans willing to take part in surveys may be more likely to vote for Democrats than those who decline to respond, potentially making the Democratic lead appear larger than it is.
Despite these concerns, most pollsters continue to expect Democrats to have an advantage in the midterms.
Republican pollster Brent Buchanan questioned the reliance on the possibility that polls could be wrong. “I think it’s telling that we’re hanging our hopes on ‘The polls are wrong,’” he told Axios. “That’s not very strong.”
The concerns come as Trump faces low approval ratings. Cook’s polling tracker puts his approval rating at 37.6%. A recent Economist/YouGov poll found that 35% of respondents approved of his performance, while 60% disapproved.
