James Gimpel, a professor at the University of Maryland, said in a report being released by the Center for Immigration Studies that many of those in the recent wave of immigrants trail native-born Americans on education and skills and favor a broader scope for government action, which makes them “ideal recruits for the Democratic Party.”

Immigrants also tend to move to urban areas, where they become further imbued with Democratic politics, he said.

“It has been a 30-year thing, and these populations continue to come in with predominantly less education and low skills, which makes them ideal recruits for the Democratic Party,” Mr. Gimpel said in an interview. “In addition, of course, they settle in areas where they’re easily socialized in the Democratic Party.”

The effects have deeply shifted politics, he said. In urban areas, immigration has accounted for an average 6 percent drop in support for Republican candidates, while across all U.S. counties the average is about a 2 percent drop.