Don't think what Trump is doing on immigration is very popular.

Writer, podcaster, and commentator on foreign affairs and politics. Runs /dropglobalnews

This mostly hinges on illegal/legal distinction. Legal immigration and the idea of it is very popular.

The idea of deporting illegal immigrants is fairly popular. 55% of Americans are in favor of deporting all illegal immigrants. The methods used are probably also a big divide

So if Trump follows a policy of just deporting illegals immigrants, it is definitely popular. If he follows a policy of reducing legal immigration, that is very unpopular