evidence: America’s immigration debate has taken a restrictionist turn. Eight years ago, Donald Trump declared that "when Mexico sends its people, they’re not sending their best," and promised to build a "big, beautiful wall" on the southern border. That rhetoric, extreme at the time, seems mild now. Today, he depicts immigrants as psychopathic murderers responsible for "poisoning the blood of our country" and claims that he will carry out the "largest deportation operation in the history of our country." [...] Political scientists have long observed that public opinion tends to move in the opposite direction of a sitting president’s rhetoric, priorities, and policies, especially when that president is an especially polarizing figure—a phenomenon known as "thermostatic public opinion." No president has kicked the thermostat into action quite like Trump. In response to his incendiary anti-immigrant rhetoric and harsh policies, including the Muslim ban and family separation, being pro-immigrant became central to Democratic identity. In 2016, only 30 percent of Democrats told Gallup they wanted to increase immigration; by 2020, that number had grown to 50 percent. In just four years under Trump, Democratic attitudes toward immigration levels warmed more than they had in the previous 15.