While the effects of a hidden Trump vote are certainly overstated by the president’s allies, that does not mean that no evidence exists that polls are missing some of his voters. A small percentage of his support is probably being undercounted, and has been in the past, public opinion experts said. And in states like North Carolina, where the margin of victory could be narrow, the undercount could make a difference between a poll being right or wrong.
“We assume the race will tighten, and as that happens, the size of the shy Trump vote could very easily come into play,†said Neil Newhouse, a Republican who led Mitt Romney’s polling in 2012.
In 2016, Mr. Newhouse said that Mr. Trump tended to score 2 or 3 points higher in phone surveys when respondents were asked to press a button to record their preferences rather than talk to a live person. In postelection polling, when he asked people if they had ever been unwilling to talk about their vote, 35 percent of Trump voters said yes. And they tended to be women from Democratic-leaning counties.
Mr. Newhouse has picked up further evidence of such reluctance recently. In polls he conducted late last month in North Carolina and Iowa, he found that one-quarter to one-third of voters answered “yes†when asked if they knew someone who is voting for Mr. Trump but would not say so to anyone but their closest friends.
“This totally confirms the notion of ‘shy Trump voters,’†Mr. Newhouse said. But, he added, if polls are undercounting some Trump voters — a group that tends to be uniquely expressive and adamant about their support for the president — no one can say by how much.
And in any case, pollsters say they have corrected one of the biggest mistakes they made in 2016, when they failed to account for the high numbers of voters without college degrees who turned out, many of whom voted for Mr. Trump. And they are including a larger pool of possible voters in surveys — not just people who say they are likely to vote, as pollsters often do — because they anticipate historic turnout.
One variable that public opinion experts are still grappling with is how the polarized political climate is affecting the accuracy of their work. Recent research has shown that conservatives fear they are more likely than moderates and liberals to be targeted for being honest about their political beliefs, though self-censorship appears to be rising among most Americans.
