Read: What was the point of Trump’s Oval Office address?

The struggle over the border wall actually provides a revealing gauge of Trump’s prospects on that front. From the start of his presidential campaign, immigration, more than any other issue, captured the potential benefits of Trump’s strategy of pursuing depth of support over breadth. Even during the 2016 Republican primaries, a majority of voters opposed deporting all undocumented immigrants in all but two of the 20 states where exit polls asked their opinion. Yet the minority of voters that supported deportation backed Trump in such preponderant numbers that they provided a majority of his votes in all but two of the 20 states.

The same pattern was evident in the general election. In the exit poll, just 41 percent of voters supported Trump’s border wall, while a solid majority of 54 percent opposed it. Yet Trump won a much higher share of the wall’s supporters (85 percent) than Hillary Clinton did of the wall’s opponents (76 percent). Roughly one-fourth of the wall’s opponents either voted for Trump (16 percent) or drifted away to a third-party candidate (8 percent).

That disparity reflected a clear trend in the exit poll. On questions about Trump’s personal characteristics—such as whether he had the experience or temperament to succeed as president—he consistently won a higher percentage of those who said “yes” than Clinton won among those who said “no.” That pattern may have reflected doubts about Clinton, a willingness to roll the dice on a political outsider, or a desire for change. But whatever the cause, the pattern was decisive: The pivotal votes that made Trump president came from voters ambivalent at best about him and key elements of his agenda.

After two years of arguing for the wall as president, Trump has shown no ability to expand its popularity. In 10 national polls conducted during his presidency, Quinnipiac University has never found support for the wall higher than 43 percent. With his Oval Office address on Tuesday night, Trump may have further consolidated support among Republicans and conservatives, which could raise that number slightly. But his focus on grisly portrayals of undocumented immigrants is unlikely to dent the preponderant opposition to the wall among all the groups that powered the Democratic takeover of the House last fall: minorities, young people, and college-educated white voters. Depending on the survey, the wall usually faces opposition from at least two-thirds of minorities and young people, and between three-fifths and two-thirds of college-educated whites.

Looking back at 2016, Trump may conclude that lopsided opposition from those groups doesn’t matter so long as he maintains strong support for the wall from his base. But there’s evidence that the voters hostile to the wall, and to many other aspects of Trump’s tenure, are less willing to give him the benefit of the doubt now than they were in 2016.