Are There Really Hidden Trump Voters?

Hillary Clinton is favored to become the next president of the United States. Yet many in Donald J. Trump’s camp remain undaunted, arguing that hidden supporters will carry him to the White House. As the polls have narrowed in the last few days, the question of whether pollsters could be missing Trump voters has become paramount. Do these unseen supporters exist?

Working with the students in our undergraduate public opinion course at Cornell, we recently commissioned a nationally representative survey of 1,461 adults (carried out by the market research company GfK from Oct. 5 to 25). To our surprise, we found previously undiscovered Trump supporters. But we also found that they are likely to stay home on Election Day.

Like many surveys, ours asked, “If the presidential election were being held today, would you vote for Hillary Clinton, the Democratic candidate; Donald Trump, the Republican candidate; other; or do not intend to vote?” Consistent with most polls during this period, Mrs. Clinton had considerably more support than Mr. Trump. However, more than 20 percent of respondents indicated that they did not intend to vote, supported another candidate or did not want to answer the question. In other words, just weeks before the election, a substantial portion of the electorate was unwilling to commit to one of the leading-party candidates. If hidden Trump supporters existed, they would have been among this uncommitted group.

At first glance, the hidden Trump supporters are indeed hidden. The proportion of uncommitted voters that identified as or leaned Democrat was slightly above the proportion that identified as or leaned Republican (49 percent versus 47 percent). These numbers contradicted the “hidden Trump supporters” argument. According to party affiliation, if the currently uncommitted decided to vote for a leading-party candidate, if anything we would expect a slight benefit to Mrs. Clinton.

But this wasn’t the whole story. It turned out that despite the prevalence of Democrats among the uncommitted, this group appeared to favor Mr. Trump.

One question on our survey, posed by our student Brianne Adler, provided evidence of hidden Trump support. That question asked whether respondents would support a proposal to increase penalties for undocumented immigrants who overstay their visas. But for half of the respondents, the question referred to “a proposal.” For the other half, it referred to “Donald Trump’s proposal.” Because chance determined the version respondents received, any differences could be attributed to the mention of Mr. Trump’s name.