it's not a protest vote for them, they believe in conservative/republican party principles.
Who is them? Who are you referring to?
i don't get why republicans aren't more open to immigration because their party benefits a lot when they become voting citizens (conservative hispanic catholics being another demo). democrats are the ones who should be hostile. they move here and become disgusted by liberal society and say these republicans have a point.
Republicanism is built on a foundation of white supremacy, so immigration (from non-white nations) will only be acceptable if the immigrants are coming in as underclass day labor and don't threaten the political, economic and cultural project of America as a white supremacist country. An interesting addendum to this conversation is the concept and history of racial classification, as throughout American history there have been non-white immigrant communities who have been reclassified as white and end up being the vanguard for the white supremacist project, immediately turning around and engage in Republicanism, aggressively policing the current non-white population.
Modern Democrats for the most part are pro-immigration because they have adopted a simplistic narrative built on racist noble savage mythology in which they view themselves as the saviour to benighted blacks and browns begging for mercy from the wicked racist white Republican/Conservative man of history. Democrats are also completely in agreement with the labor underclass argument of Republicanism though.