Why immigration is a better issue for Trump than it was in 2020

The issue of immigration has fueled former President Donald Trump's dominance over the Republican Party for the past nine years. When he first ran for office, negative views of immigrants were an important factor in him winning the GOP nomination. Those views were an even stronger predictor of voting for him in the 2024 primaries.

It's no surprise, then, that immigration was the defining issue of last month's Republican National Convention. Multiple speakers criticized President Joe Biden's immigration record, often in misleading ways. Trump announced Sen. JD Vance, a fellow immigration hawk, as his running mate. A sea of "Mass Deportation Now" signs swamped the convention floor. And in his own speech, Trump called illegal immigration an "invasion that is killing hundreds of thousands of people a year" and promised the "largest deportation operation in the history of our country."

Now that Biden is no longer running, Republicans have quickly transitioned to attacking Vice President Harris's immigration record as the so-called "border czar." Last week, Vance toured the U.S.-Mexico border in Arizona, where he proclaimed, "It's hard to believe, until you see it with your own eyes, just how bad the policies of the Kamala Harris administration have been when it comes to the southern border."

But these appeals are no longer just for hardcore supporters. They've also become a good general-election strategy. Trump's immigration positions have much more support now than they did in 2016 or 2020.

Trump's victory in 2016 might have seemed like a mandate for his restrictive views. But a backlash against the Trump administration's immigration policies pushed public opinion about immigration to the left. By 2020, the share of Americans who favored increased levels of immigration (34 percent) surpassed the share favoring decreased levels (28 percent) in Gallup polling for the first time since the organization began asking the question in 1965.

As a result, Biden had a sizable advantage over Trump on the issue in 2020. Four years ago, he led Trump by over 15 percentage points on the question of which candidate would do a better job of handling immigration.

But public opinion about immigration has swung sharply back to the right since Biden became president. There has been an 11-point increase in the share of Americans who say that "immigrants drain national resources," a 12-point increase in support for deporting undocumented immigrants and record support for the U.S.-Mexico border wall. There has been an even more dramatic change in support for decreasing immigration levels. The share of Americans favoring such reductions surged from 28 percent in May 2020 to 55 percent in June 2024 — the highest percentage recorded in Gallup's polling since October 2001.

In a new Democracy Fund report, John Sides, Robert Griffin and I explain what has happened. The public's immigration attitudes have largely followed the changing discourse over the issue since Biden became president. As politicians and the media have shifted from criticizing unpopular Trump-era policies like family separation to expressing concern about the record number of border crossings under Biden, the opinions of average Americans shifted in a similar way.

Obviously, those concerns are much more prevalent among Republican politicians and conservative media. We show, for example, a sharp spike in discussion of immigration on outlets like Fox News. As a result, this rightward shift in public opinion is more pronounced among Republican voters. As of 2024, a record-high 88 percent of Republicans want to decrease immigration, up from 48 percent in 2020.

But Democratic attitudes have changed, too. The percentage who wants to reduce immigration has increased from 13 percent in 2020 to 28 percent in 2024. This arguably reflects the prevailing messages from Democratic leaders, who have also expressed concerns about the situation at the border. Indeed, in January, Biden called it "broken."

The public's growing opposition to immigration has helped turn Trump's liability into one of his greatest strengths. Before Biden dropped out, polls consistently showed that far more voters trusted Trump on this issue than Biden. Similarly, Trump's biggest issue advantage over Harris in a YouGov poll conducted shortly after Biden's withdrawal was on which candidate would do a better job of handling immigration as president; he led her on that question by a 45-percent-to-30-percent margin.

Immigration is also a more important issue to voters than it was four years ago. Our Democracy Fund report shows that the share who say immigration is "very important" grew from 47 percent in 2020 to 54 percent in 2024, with an 11-point increase among independents. Likewise, immigration was named as the country's top problem for a record three straight months in Gallup polls from February, March and April.

These dramatic swings in immigration attitudes over the past eight years dovetail with one influential account of public opinion: the thermostatic model of policy attitudes. In the thermostatic model, the public's policy attitudes shift against the current president's policies in response to real or perceived changes in the status quo — just like a thermostat will cool down a house when it gets too hot, or heat it up when it gets too cold.

Thermostatic patterns have long been documented in attitudes toward government spending and programs. But for a long time, issues related to immigration did not display these thermostatic patterns.

That no longer appears to be the case, largely because the Democratic and Republican parties themselves have changed. With the parties pushing different immigration policies even more than in the past, the public appears to be pushing back, with their opinions moving to the left under Trump and back to the right under Biden.

That raises a cautionary note for Trump. If he wins a second term, he has promised a mass deportation of undocumented immigrants and sharp limits on legal immigration. Such a dramatic pivot in policy is likely to push public opinion in a liberal direction once again. So even if immigration helps Trump win in 2024, his advantage on the issue may prove fleeting.