At The Forum, James Gimpel has an article titled "From Wedge Issue to Partisan Divide: The Development of Immigration Policy Opinion after 2016." The abstract:
President Trump won an Electoral College majority in 2016 bolstered by voters who supported him, but not the previous nominee, Mitt Romney. Evidence suggests that a campaign promising a more restrictive immigration policy was the key to this improved performance among cross-pressured voters. In the months since inauguration day 2017, however, voters did not remain unaware of the administration’s programmatic steps on immigration and the opposition they encountered. I interpret evidence from a panel survey to suggest that voters gained knowledge about immigration policy after 2016, and began to align their policy views with the positions of their favored political parties. Inasmuch as voters’ policy positions become identical with their party preference, the potential for immigration policy to again act as a wedge issue in 2020 is greatly reduced. President Trump’s 2020 campaign may be able to mobilize more base voters given this increase in policy-party congruence but he may not be as successful as in 2016 in attracting crossover voters.