But now, in the middle of the general election campaign, Trump is easily the most unpopular major party nominee in modern times. And his historic unpopularity may have also eroded support for the border wall.
The graph shows the trend in support for the border wall over the past year.
The Pew Research Center gauged support for the border fence before and after June 2015, when Trump announced his candidacy. The percentage supporting the border fence was the exact same in 2007, 2011, and 2015: 46 percent. However, that dropped to 36 percent in March 2016.
In CBS/New York Times polls, public support for “building a wall along the US-Mexico border to try to stop illegal immigration” also dropped — from 45 percent in January 2016 to 39 percent in July.
The results from the RAND Corp’s Presidential Election Panel Survey (PEPS) are even more telling. The PEPS data track changes in support for the wall among the same individuals who were interviewed in December-January and July-August 2016. Their support for the border wall dropped from 48 percent to 38 percent.
More importantly, the PEPS data reveal who was particularly likely to shift to opposing the border wall: people who did not like Trump in 2015.
Support for the wall declined by 14 points among those who rated Trump unfavorably in December 2015, and 15 percentage points among those who preferred Hillary Clinton over Trump. Meanwhile, support for the wall has been much more stable among Trump’s early supporters.
This pattern remains intact after accounting for partisan, ideological, and demographic factors. It appears, then, that Trump’s strong support for the border wall has made this policy considerably less popular with the American public. This fits with other evidence showing that Americans often change their policy positions to match those held by their preferred presidential candidates.
The border wall may not be Trump’s only position that is backfiring. Muslims have become more popular since Trump proposed banning the religious group from entering the country in December 2015.
Polling conducted for the Brookings Institution shows that favorability ratings of Muslims are up nine percentage points, from 53 percent in November 2015 to 62 percent in June 2016. This increased support for Muslims is concentrated among those predisposed to dislike Trump —Democrats and independents.
A few months ago, Mitt Romney expressed concern that Trump’s presidential campaign could lead to “trickle-down racism.”
But Trump is so widely disliked that his hostile statements about minority groups may actually have produced the opposite: trickle-down tolerance.
Michael Tesler is associate professor of political science at UC Irvine and author of Post-Racial or Most-Racial? Race and Politics in the Obama Era.