Once again, polls underestimated Trump. Experts only have a hunch why | U.S. & World [Video]

By Jason Lange

WASHINGTON (Reuters) – Following Republican President-elect Donald Trump’s resounding victory in this month’s election, some U.S. pollsters are scrambling to understand why their surveys once again underestimated his support among American voters.

Polls before the Nov. 5 vote had shown Trump trailing Democratic Vice President Kamala Harris by 1 percentage point, according to an average of dozens of national opinion polls compiled by 538, a website on data analysis for politics and sports. With vote tallies nearly finalized, Trump led Harris nationally by 2 percentage points: 50% to 48%.

That undershoot of 3 points follows polls in 2020 that underestimated Trump’s national margin by 4 points and in 2016 that underestimated his performance by 2 points, according to 538’s averages.

Those results are all largely within pollsters’ normal margins of error — a measure of statistical precision influenced by a variety of factors including the number of respondents to a …